General remarks on chloranthy and frondescence.—Moquin remarks with justice that the position of the flowers on the axis is of importance with reference to the existence of chloranthy. Terminal flowers are more subject to it than lateral ones, and if the latter, by accident, become terminal, they seem peculiarly liable to assume a foliaceous condition. Kirschleger says, that in Rubus there are two sorts of chloranthy, according as the anomaly affects the ordinary flowering branches, or the leafy shoots of the year, the summits of which, instead of developing in the customary manner, terminate each in one vast and long inflorescence, very loose and indeterminate, and with axillary flowers.[293]

On the whole, taking in consideration cases of partial frondescence, as well as those in which most of the parts of the flower are affected, phyllody would seem to be most common in the petals and carpels, least so in the case of the stamens and sepals. It is more common among polysepalous and polypetalous plants than in those in which the sepals or petals are united together.

The causes assigned for these phenomena are chiefly those of a nature to debilitate or injure the plant; thus it has been frequently observed to follow the puncture of an insect. M. Guillard[294] gives an instance in Stellaria media where the condition appeared to be due to the attacks of an insect Thrips fasciata. Still more commonly it arises from the attacks of parasitic fungi, e.g. Uredo candida, in Crucifers, &c.

In other cases it has been observed when the plants have been growing in very damp places, or in very wet seasons, or in the shade, or where the plant has been much trampled on. This happens frequently with Trifolium repens. The frequency with which the change is encountered in this particular species is very remarkable; it is difficult to see why one species should be so much more subject to the kind of change than another of nearly identical conformation.

It might at first be supposed that the same causes that bring about the complete substitution of leaf-buds for flower-buds (see Heterotaxy) would operate also in the partial substitution of leaves for other parts of the flower, but it will be seen that the inducing cause, whether similar or not in the two cases respectively, acts at different times; in the one case, it is not brought into play until the rudiments of the flower are already formed, whereas in the other the influence is exerted prior to the formation of the flower. So that while the formation of leaf-buds in place of flower-buds may be and generally is due to an excess of nutrition, inducing over activity of the vegetative organs, the production of phyllomorphic or chloranthic flowers may be owing rather to a perversion of development arising from injury or from some debilitating agency. The discrepancies in the assigned causes for the conditions above mentioned may, therefore, in great measure, be attributed to the different periods at which the causes in question operate.

The following list may serve as a guide to the plants most frequently the subjects of chloranthy, but reference should also be made to preceding and subsequent sections, and to that relating to prolification of the inflorescence.

Aquilegia vulgaris. Chelidonium majus. Corydalis aurea. Nymphaea Lotus! *Brassica oleracea! Bunias. Hesperis matronalis. *Sinapis arvensis! Sisymbrium officinale. Erucastrum canariense. Diplotaxis tenuifolia. Lychnis dioica! Cerastium glomeratum! triviale. Stellaria media. Poterium polygamum. Torilis anthriscus. Seseli, sp. Selinum caruifolium. Epilobium hirsutum! Begonia fuchsioides. Gomphia, sp. Scabiosa Columbaria. Dipsacus fullonum. Matricaria Parthenium. Calendula officinalis. Campanula pyramidalis. Reseda odorata! Vitis vinifera. Dictamnus Fraxinella! Triumfetta, sp.! *Tropaeolum majus! Rhamnus Frangula. *Trifolium repens! Lupinus, sp. Rosa diversifolia! Potentilla nepalensis. argentea. Fragaria vesca! Geum rivale. Rubus fruticosus. caesius. Saxifraga foliosa. Verbascum phlomoides. Scrophularia nodosa. aquatica! *Primula sinensis! Lysimachia Ephemerum. Anagallis arvensis. Webbiana. Nicotiana rustica. Anchusa ochroleuca. Myosotis caespitosa. Stachys sylvatica. Gilia capitata. Euphorbia segetalis. Rumex arifolius. scutatus. Juncus lampocarpus. uliginosus.

In addition to the publications before cited the following may be named as containing valuable information on the subject of this chapter.

Jaeger, 'Missbild. Gewaechs.,' 1814, p. 83, Trifolium repens. For other accounts of similar malformations in the same plant, see Schmitz, 'Linnaea,' xv, p. 268. Unger, 'Flora' (B. Z.) xxv, p. 369. Caspary, 'Schrift. der. Physik. oekon. Gesellsch. zu Koenigsberg,' 2, 1861, p. 51, tabs. ii, iii. Fleischer, 'Missbilld. verschied. Cult. Pflanz.,' 1862, p. 55, &c., t. v, vii, &c. For Primula see Brongniart, 'Ann. Sc. Nat.,' ser. 2, t. i, p. 308. A. P. and Alph. De Candolle in 'Neue Denkschrift.' Morren, C., 'Bull. Acad. Roy. Belg.,' xix, part 2, p. 539. Molkenboer, 'Tijdschr. voor Natuurl. Geschied.,' 1843, p. 355, tabs. vi, vii. Marchand, 'Adansonia,' iv, p. 167 and p. 159. Anagallis, p. 171, Lonicera, p. 83, Juncus. For other plants see Fresenius, 'Mus. Senk.,' 2, p. 35, &c. Norman, 'Ann. Sc. Nat.,' ser. 4, 1858, vol. ix, p. 220. Christ, 'Flora' (B. Z.) 1867, p. 376, tabs. v, vi, Stachys. Cramer, 'Bildungsabweich.,' p. 26, &c. Baillon, 'Adansonia,' ii, p. 300. Moquin-Tandon, 'El. Ter. Veg.,' p. 230. Schauer's translation, p. 220. Hallier, 'Phytopathologie,' p. 160.

FOOTNOTES:

[245] Engelmann makes use of the word frondescence in the same cases. 'De Anthol.,' p. 32, Sec. 38, while Morren adopts the term Phyllomorphy, 'Lobelia,' p. 95.

[246] See Schlechtendal, 'Bot. Zeit.,' vol. xv, 1857, p. 873; also Marchand, 'Adansonia,' iv, p. 156.

[247] For instances of similar changes in Composites, see De Candolle, 'Prod.,' t. vi, p. 571, Centaurea Jacea phyllocephala. Clos, 'Ann. Sc. Nat.,' ser. iii, tom. xvi, 1851, p. 41. 'Science Gossip,' 1865, p. 104, &c.

[248] Kickx, 'Bull. Acad. Belg.,' t. xviii, part 2, p. 288.

[249] Weber, 'Verhandl. Nat. Hist. Vereins. f. Preuss.,' &c., 1860, p. 381.

[250] Weber, loc. cit.

[251] Sauter, 'Flora v. Bot. Zeit.,' 1831, p. 11.

[252] 'Descr. et Icon. Plant.' tab. 20.

[253] For references see p. 115; see also to Eichler, 'Excurs. Morpholog. de format. flor. Gymnosperm.,' in "Mart. Flor. Brasil," abstracted in English in 'Natural History Review,' April, 1864.

[254] "Calyx tunc plane non differt a foliis proxime ipsi praecedentibus." Wolff, 'Theor. Gener.,' Sec. 114. Linn., 'Proleps.,' Sec. 6. Goethe, 'Versuch.,' Secs. 31-38.

[255] 'Bull. Soc. Bot. France,' vol. viii, 1861, p. 697.

[256] 'Organ. Veget.,' t. i, p. 492, pl. xxxii, f. 6.

[257] This distinction between laminar and vaginal venation is well seen in cases like Mussaenda, Calycophyllum, or Dipterocarpus, where the enlarged calycine segment has a strictly vaginal arrangement of its veins, very different from that which occurs in the true leaf-blades. These are cases, therefore, where the sheath of the leaf is unusually enlarged, and are not to be referred, as is often done, to metamorphosis of one or more sepals to perfect leaves. Prolified roses, cherries, &c., furnish frequently parallel cases. With reference to Mussaenda, C. Morren held the view that the petal-like sepal was really a bract adherent to the calyx, and incorporating with itself one of the calycine lobes—"soudee au calice et ayant devoree, en englobant dans sa propre masse, un lobe calicinal." The Belgian savant considers this somewhat improbable explanation as supported by a case wherein there were five calyx lobes of uniform size, and a detached feather-veined leaf proceeding from the side of the ovary lower down ('Bull. Acad. Belg.,' xvii, p. 17, Fuchsia, p. 169).

[258] In this order Agrostemma Githago offers an illustration of a normally leafy calyx.

[259] 'Bull. Bot.,' i, p. 6.

[260] Wolff's original opinion was that the stamens were equivalent to so many buds placed in the axil of the petals or sepals (see 'Theoria Generationis,' 1759, Sec. 114)—an opinion which more recently has received the support of Agardh and Endlicher. Wolff himself, however, seems to have abandoned his original notion, for in his memoir, "De formatione intestinorum praecipue tum et de amnio spurio aliisque partibus embryonis gallinacei, nondum visis," &c., in 'Comm. Acad. Petrop.,' xii, p. 403, anno 1766, he considers the stamens as essentially leaves. See also Linn. 'Prolepsis,' Sec. viii; Goethe, 'Metam.,' Sec. 46.

[261] Mueller (Argov.), in 'Mem. Soc. Phys. et d'Hist. Nat. Genev.,' t. xvii.

[262] "If we keep in view the observations which have now been made, we shall not fail to recognise the leaf in all seed-vessels, notwithstanding their manifold forms, their variable structure, and different combinations."—(Goethe, 'Metam.,' Sec. 78.) Wolff, 'N. Comm. Acad. Petrop.,' 1766, xii, p. 403, expresses precisely the same opinion as to the nature of the seed-vessel.

[263] 'El. Terat. Veg.,' p. 205.

[264] 'Ann. Sc. Nat.,' 4th series, vol. ix, p. 209.

[265] 'Adansonia,' iv, p. 70. A similar deviation has been observed by M. van Tieghem in the ovary of Tropaeolum majus, 'Bull. Soc. Bot. Fr.,' 1865, p. 411.

[266] Planchon et Mares, 'Ann. Sc. Nat.,' ser. 5, vol. vi, 1866, p. 228, tab. xii.

[267] 'Act. Acad. Nat. Cur.,' 22, 11. 1850, p. 543, t. v, vi.

[268] 'Neue Denkschrift der allg. Schweiz. Gesellsch.,' band v. p. 9, tab. 3, 4.

[269] 'Ann. Sc. Nat.,' 2 ser., vol. i, p. 308, pl. ix, c.

[270] 'Adansonia,' vol. iv, pp. 159, 171.

[271] 'Bildungsabweichungen,' &c., tab. iv, figs. 1, 2, 21, 28, 29, &c.

[272] 'Bull. Soc. Bot. France,' viii, p. 395.

[273] 'Notulae,' p. 125, atlas, pl. xxxv; and 'Journals of Travels,' 1847, p. 475, Lonicera.

[274] 'Ann. Science Nat.,' 3rd ser., vol. ix, p. 86, tabs. 5, 6.

[275] 'Comptes Rendus,' vol. xviii, March 25th, 1864, and 'Ann. Sc. Nat.,' 3 ser., vol. ii, p. 32.

[276] 'Mem. Acad. Sc. Toulous.,' ser. 5, vol. iii.

[277] 'Bildungsabweich. Pflanz. Famil.,' p. 89, tab. xi.

[278] 'Bull. Soc. Bot. Fr.,' 1865, p. 411.

[279] Translated in 'Ann. Sc. Nat.,' 4th series, t. xiv, p. 24.

[280] The calyx is not unfrequently excepted.

[281] 'Bull. Bot.,' t. i, p. 6.

[282] Lindley, 'Theor. Horticult.,' ed. 2, p. 84, f. 17.

[283] Gris, 'Bull. Soc. Bot. Fr.,' 1858, vol. v, p. 261, and 'Ann. Sc. Nat.,' ser. 4, vol. ix, p. 80. Planchon, 'Flore des Serres,' vol. i, 1856, p. 129.

[284] 'Flora,' 1856, p. 711.

[285] 'Theory of Horticult.,' ed. 2, p. 90, f. 25.

[286] As considerable interest attaches to the "Plymouth strawberry," and very little is known of it in this country, or on the continent, the author gladly avails himself of this opportunity of inserting an account of it, for which he is indebted to the kindness of Dr. Robert Hogg.—The Plymouth Strawberry (Fragaria vesca fructu hispido) is a sort of botanical Dodo upon which many have written, and which few have seen. Many years have elapsed since it was first discovered; and although a century and a half have passed since there was any evidence of its existence, it serves still as an illustration for students in morphology of one of those strange abnormal structures with which the vegetable kingdom abounds.

It is to old John Tradescant we are indebted for the earliest record of this plant. Johnson, in his edition of 'Gerard,' says; "Mr. John Tradescant hath told me that he was the first that tooke notice of this strawberry, and that in a woman's garden at Plimouth, whose daughter had gathered and set the roots in her garden, in stead of the common strawberry; but she, finding the fruit not to answer her expectation, intended to throw it away; which labour he spared her in taking it and bestowing it among the louers of such varieties, in whose garden it is yet preserved." Doubtless one of those "lovers" was his friend John Parkinson, who, in the year 1629, thus wrote concerning it: "One strawberry more I promised to shew you, which, although it be a wilde kinde, and of no vse for meate, yet I would not let this discourse passe without giuing you the knowledge of it. It is in leafe much like vnto the ordinary, but differeth in that the flower, if it haue any, is greene, or rather it beareth a small head of greene leaues, many set thicke together like vnto a double ruffe, in the midst whereof standeth the fruit, which, when it is ripe, sheweth to be soft and somewhat reddish, like vnto a strawberry, but with many small harmlesse prickles on them which may be eaten and chewed in the mouth without any maner of offence and is somewhat pleasant as a strawberry; it is no great bearer, but those it doth beare, are set at the toppes of the stalks close together, pleasant to behold, and fit for a gentlewoman to weare on her arme, &c., as a rairitie in stead of a flower."

Merret, in his 'Pinax.' published in 1667, says he found it growing in the woods of Hyde Park and Hampstead, and Zanoni was the first to figure it (with the exception of Parkinson's rude woodcut) in his 'Istoria Botanica,' published in 1675. It is mentioned by Morison and also by Ray, the latter of whom inserts it in his Synopsis, but without any habitat; though in his 'Historia Plantarum' he says: "Cantabrigiae in horto per aliquot annos colui." From this time henceforth the Plymouth strawberry has become a botanical Dodo, nothing more having been seen or heard of it except the mere record of the name. In 1766, M. Duchesne informed the world of the generosity of "M. Monti, Docteur de Philosophie et de Medecine a Boulogne en Italie," who divided with him a dried specimen taken from his own herbarium, "Ce present pretieux m'ote toute incertitude sur la nature de ce Fraisier et sur ses caracteres monstrueux. Il paroit ne pas avoir aujourd'hui plus d'existence."

[287] 'Bull. Soc. Bot. France,' 1856, vol. iii, p. 477.

[288] 'Ann. Sc. Nat.,' 3 ser., vol. ix, p. 86, tabs. v, vi.

[289] 'Bull. Soc. Bot. France,' vol. viii, 1861, p. 695.

[290] Ibid., vol. iii, 1856, p. 475.

[291] 'Flora,' 1856, p. 712.

[292] 'Trans. Linn. Soc.,' vol. xxvi, p. 37.

[293] 'Bull. Soc. Bot. France,' 1862, vol. ix, p. 36, tab. i, and also p. 291.

[294] Ibid., 1857, vol. iv, p. 761.



CHAPTER II.

METAMORPHY OF THE FLORAL ORGANS.

One of the main arguments adduced by Goethe and others in support of the now generally received doctrine of the essential morphological identity of the various whorls of the flower is derived from the frequent appearance of one organ in the guise of another. The several parts of the flower become, as it is said, metamorphosed; sometimes the change is complete, while at other times there may be every conceivable intermediate condition between one form and another. The sense in which the terms metamorphosis, substitution, transformation, and the like, are herein used has already been explained. For the convenience of arrangement, metamorphosis of the parts of the flower may be divided into several subdivisions, according to the particular organ affected, and according to the special kind or degree of change manifested, the main subdivisions being here classed as Sepalody, Petalody, Staminody, and Pistillody.

Sepalody of the petals.—This change, spoken of by most authors as retrograde metamorphosis of the petals into sepals, or as a substitution of sepals for petals, is obviously a condition that is in most cases hardly distinguishable from virescence of the corolla, or from multiplication of the sepals. Nor is this of much consequence unless there are some special structural features which render the discrimination a matter of importance, in which case the difficulty is generally easily surmounted. The flower of the Saint-Valery Apple may perhaps be cited under this head. In the flower in question there are neither stamens nor petals, unless the second or inner of sepals be considered as sepaloid petals (fig. 152).



M. Alph. de Candolle[295] describes an instance in Primula Auricula in which the corolla had assumed the appearance of the calyx, but neither calyx nor corolla in this case possessed perfect stomata.

This malformation is much less common than the converse one of calycanthemy. Many of the recorded instances of so-called metamorphosis of the parts of the flower to sepals have occurred in monocotyledonous plants, or others in which the calyx and corolla are of the same colour, and constitute what is frequently termed the perianth; and as this is usually brightly coloured (not green) it is more convenient to group the metamorphoses in question under the general term Petalody, which thus includes all those cases in which the organs of the flower appear in the form of coloured petal-like organs, whether they be true petals or segments of a coloured perianth. As the morphological difference between the organs is one of position merely, there is little objection to be raised to this course, the less so as the term petalody merely conveys an idea of resemblance and not of absolute identity.

Petaloid coloration of the ordinary leaves, or of the bracts, is mentioned under the chapter relating to colour.

Petalody of the calyx—Calycanthemy.—As with the bracts, so the calyx in certain instances is naturally coloured, as in Delphinium, Tropaeolum, and others. In Mussaenda, Calycophyllum, Usteria, &c., one or more of the calyx lobes become enlarged normally. Considered teratologically, petaloid coloration of the sepals is either general or partial; in the latter case the nerves retain their green colour longest. There is in cultivation a variety of the primrose called Primula calycanthema, in which the upper part of the calyx becomes coloured, so that the flower seems to have two corollas placed one within the other; a similar thing happens in Mimulus, in which plant, as the calyx is permanent while the corolla is deciduous, the coloured calyx is a great advantage in a horticultural point of view. Morren[296] says that in order to produce the fine colour of the calyx of Primula officinalis (var. smaragdina) the Belgian gardeners cut away the corolla in a very early stage, and that in consequence the colouring matter proper to the corolla is developed in the tube of the calyx, the edges of the limb remaining green, the middle of the limb being purple (Primula tricolor).



Under this head may be mentioned the occurrence of tubular sepals in place of the ordinary flat ones in Helleborus olympicus; only two of the sepals were thus affected in a specimen recently observed—a third exhibited an intermediate condition.

The normal coloration of the calyx occurs most frequently in polysepalous calyces; teratological coloration, on the other hand, occurs especially in gamosepalous flowers. This assertion is borne out by the frequency of the change in the plants already mentioned, and also in the following:—Campanula persicifolia, Anagallis arvensis, Gloxinia, Syringa persica,[297] Calceolaria, &c. &c. In the last-named plant one or more of the lobes of the calyx may frequently be seen replaced by a slipper-like petal.

Among polysepalous plants petaloid sepals have been observed in Ranunculus auricomus, Rubus caesius, &c. Fleischer also describes a case of this kind in Carum carui.[298]

It will be seen from the above that in the majority of cases there is no real metamorphosis or substitution of petal for calyx, but simply an alteration in colour; nevertheless, a change in form may accompany a change of colour: this happens especially if there has been any displacement of organs. Thus, if, in an orchidaceous plant, a sepal be displaced from any cause, or a petal be twisted out of its natural position to occupy the place of an absent sepal, that petal will be sepal-like in form, and vice versa.

Petalody of the stamens.—A petaloid condition of the stamens is one of the commonest of all malformations. A large number of so-called double flowers (flores pleni)[299] owe their peculiar appearance to this circumstance.

It is necessary to distinguish carefully this petaloid development of the stamens from the corresponding condition of the pistils, and from that kind of doubling which is a result of multiplication of the corolla, as in Datura, Campanula, Primula, &c. (flores duplices, triplices, &c.), or from that produced by true median prolification (flores geminati, &c.).

In cases of true petaloid development of the stamens there are usually numerous intermediate forms between that of the true petals and that of the perfect stamens; indeed, in Nymphaea, Canna, and in some other plants, such a transition occurs normally. Petalody of the stamens may occur either without material change in the flower or it may exist in combination or in conjunction with an increased development of parts (Multiplication), or with a similar change in the carpels, and it is either partial or complete.

Among the flowers in which petaloid development of the stamens happens most frequently may be mentioned those in which the calyx is normally coloured, as in Nigella damascena, Aguilegia, and Delphinium.

M. Alph. de Candolle, in the 'Neue Denkschriften,' 1841, described and figured a singular form of Viola odorata, known under the name of "Bruneau," in Switzerland, in which the stamens are absent, and their place supplied by a second row of petals, within which is a third series of petals, representing, says M. de Candolle, the inner row of stamens that theory suggests should exist in the natural condition. Moreover, the carpels in this variety are five in number instead of three. In Erica Tetralix the corolla may not unfrequently be found divided to the base into its constituent petals, and the place of the stamens occupied by a series of petal-like structures entirely destitute of anther.

In monocotyledonous flowers, especially those with a coloured perianth, the substitution of segments of the perianth for stamens occurs not unfrequently. M. Seringe has observed this in the stamens of Lilium Martagon, and there is in cultivation a variety of the white lily, Lilium candidum, sometimes called the double white lily, in which the segments of the perianth, in place of being arranged in two rows, are greatly increased in number, and disposed in a spiral manner. In these flowers, not only are the stamens and pistils thus modified, but also the upper leaves of the stem. In so-called double tulips there is likewise a replacement of stamens by coloured segments of the perianth, but this happens generally in connection with an increase in the number of organs. Moquin-Tandon remarks having seen in a garden in the environs of Montpelier a tulip, the stamens of which showed all possible stages of transition between the form proper to them and that of the perianth. The pistil in this case was transformed into several small leaves. Similar appearances have been observed in Iris, Hyacinths, Narcissus, Colchicum, and Crocus. M. Fournier[300] describes a flower of Narcissus Tazetta from within the normal perianth of which sprang a second one, equally provided with a cup and occupying the space usually filled by the stamens. Flowers of Narcissus poeticus may also be met with in which the stamens are replaced by six distinct segments exactly resembling those of the perianth in miniature.[301]



From an examination of these flowers it becomes evident that petalification is brought about in different flowers in different ways; sometimes it is the filament which becomes petaloid, sometimes the anther-lobes, while at other times it is the connective which assumes the appearance of petals.[302] For instance, in Solanum tuberosum, S. Dulcamara, in Anagallis, in Fuchsia, and some other plants, the anther-lobes themselves become petaloid, while the filament remains unchanged.

In gardens two distinct varieties of Columbine are cultivated, the one in which the filaments are dilated into the form of flat petals almost entirely or quite destitute of anthers, while in the other the filament is present in its usual form, but the anther is developed in the shape of a tubular hood or spur.

De Candolle[303] observes that in the Ranunculaceae the species of Clematis become double by the expansion of the filament, those of Ranunculus by the dilatation of the anther, and those of Helleborus by the petal-like development of both filament and anther. In some cases even on the same plant all three modifications may be seen, as in Camellias, some of which may be found with petaloid filaments with anthers on the top, others with the filaments unchanged, but supporting petaloid anthers, while in others it is the connective alone which is petal-like. Where the flower naturally contains a large number of stamens, as in Mallows, Roses, Magnolias, &c., petaloid expansion of the filament is most common, though it is by no means confined to such flowers, the change occurring in Allamanda cathartica, Jasminum grandiflorum, and many other flowers with few stamens. A similar change in the anther and connective takes place more frequently in flowers where the number of stamens is smaller, but there are of course numerous exceptions to this rule.

In those cases where there is more than one row of stamens, the outermost are most liable to this change: thus in Saxifraga decipiens, as shown by Ch. Morren,[304] the outer series of stamens—those opposite to the sepals—become first affected, and, at a more advanced stage, the inner row also; and this is the case in most flowers that have their stamens in two rows. Occasionally it happens that an outer series of stamens is abortive, or wholly suppressed, while the inner row becomes petalodic; this was the case in some flowers of Lilium auratum lately exhibited by Messrs. Veitch.

Those flowers in which only a portion of the stamens undergo this change are called semi-double, while in other cases that will be hereafter mentioned, not only are the stamens thus rendered petaloid, but their number is also augmented, as in most double roses, pinks, anemones, poppies, &c.

In some double flowers, in which the stamens assume more or less completely the appearance of petals, a singular appearance is afforded by the presence of four wing-like processes emanating from the central filaments, two on each side, so that the arrangement may be compared to two sheets of paper folded in the centre and adherent in that situation, though perfectly separate elsewhere, except sometimes at the top, where they form a sort of hood. This change results from an imperfect petalody of the anther; the two wings on each side of the central vascular cord represent the front and back walls of an anther lobe, or rather of that portion of the anther which, under ordinary circumstances, produces pollen. In the malformed flowers no pollen is formed, at least in the more complete states of the malformation, but the walls of the anther lobe become preternaturally enlarged, and petaloid in texture and appearance. This change occurs in some semi-double rhododendrons and azaleas, in crocuses, and in a species of violet found at Mentone by Mr. J. T. Moggridge.

There are numerous intermediate forms wherein the wing-like processes may be traced all the way along the filament till they ultimately lose themselves in the anther-lobes, with which they become continuous. In some cases, as in Crocus and Rhododendron, this is shown even more clearly by the existence of two perfect pollen-sacs or quarter-anthers, the remaining portions being petaloid and continuous with the dilated filament. Not unfrequently these semi-petaloid stamens adhere to the fronts of the petals, and then it appears, at a first glance, as if three organs were stuck together, one in front of another, while in reality there are but two.[305] (See ante, p. 35, fig. 12.)



The change in the anther, above alluded to, must not be mistaken for that far more common one in which only a small portion of the anther becomes petaloid, forming a sort of lateral wing or appendage to the polliniferous portion, as happens normally in Pterandra, and is common in some double fuchsias. In this latter instance there is but a single wing, and the nature of the case is obvious.

Double flowers of Orchidaceae generally arise from petalification of the filaments, with or without other coincident changes. What makes double flowers in this order the more interesting is the development, in a petaloid condition, of some or all of those stamens which under ordinary circumstances are wholly suppressed, so that the morphological structure of the flower, at first a matter of theory, becomes actually realised. Fig. 156 is a diagram showing the presence of two additional labella within the ordinary one in a species of Catasetum, and representing two petaloid stamens, thus evidently completing the outer staminal whorl, of which there is usually but a single representative (see Peloria, Multiplication, Prolification). In some of these double orchids it is, however, necessary not to confound a petaloid condition of the existing column with the development of usually suppressed stamens in a petaloid form. Thus, in Lycaste Skinneri the column is frequently provided with two petal-like wings, which might readily be supposed to be two stamens of the inner whorl adherent to the column; a little attention, however, to the relative position of these adventitious wings is generally sufficient to enable the observer to ascertain the true nature of the appearance.[306]



Some forms of duplicate or hose in hose corollas are apparently due, not so much to the formation of a second corolla within the first, as to the presence of an inner series of petal-like stamens, which, by their cohesion, form a second pseudo-corolla within the first. The staminal nature of this pseudo-corolla is inferred from the occasional presence of anthers on it.[307] In Datura fastuosa, as well as in Gloxinia, a pseudo-corolla of this kind sometimes occurs with the addition of a series of petaloid stamens attached to its outer surface.[308]

When the petalody specially affects the anther-lobes, as in Arbutus, Petunia, Fuchsia, &c., the venation of the petal-like portion is very frequently laminar, thus tending to show that the anther is in such cases really a modification of the blade of the leaf; but as, on the other hand, we often find petal-like filaments bearing pollen-sacs on their sides, it is clear that we must not attribute the formation of pollen to the blade of the leaf only, but we must admit that it may be formed in the filament as well.[309]



Petalody of the connective is of less frequent occurrence than the corresponding change in the other portions of the stamen. It may be seen in some forms of double columbine,[310] in which the connective forms a tubular petal or nectary, and in double petunias and fuchsias. When it occurs, the true anther-lobes are usually atrophied, and little or no pollen is formed.

An occurrence of this nature in Tacsonia pinnatistipula, in conjunction with the partial detachment of the stamens from the gynophore, led Karsten to establish a genus which he called Poggendorffia.[311]

From the subjoined list of genera in which petalody of the stamens, in some form or other, has been observed, it will be seen that it happens more often in plants with numerous distinct organs (Polypetalae, Polyandria, Polygynia, &c.) than in other plants with a smaller number of parts, and which are more or less adherent one to the other. The tendency to petalification is, moreover, greater among those plants which have their floral elements arranged in spiral series, than among those where the verticillate arrangement exists; and in any given flower, if the stamens are spirally arranged while the carpels are grouped in whorls, the former will be more liable to petalody than the latter, and vice versa. It has been before remarked, that this condition is far more common in plants whose petals, &c., have straight veins, like those in the sheath of a leaf, than in those the venation of which is reticulate, as in the blade of the leaf. It must also be remembered that in the same genus, even in the same species, different kinds of doubling occur. Familiar illustrations of this are afforded in the case of anemones, columbines, fuchsias, and other plants.

The existence of "compound stamens" in some flowers, as pointed out by Payer, and others, and the researches of Dr. Alexander Dickson, confer additional importance on the subject of petalody, and necessitate the examination of double flowers with special reference to these compound stamens, and to the order of their development.[312] The presence of these compound stamens affords a satisfactory explanation of the appearance in some double Malvaceae, wherein the tufts of adventitious petals are very liable to be mistaken for buds, produced by axillary prolification in the axils of the petals, but which are in reality compound and petaloid stamens. At other times, however, true axillary prolification exists in these flowers; but then the supplemental florets have always a calyx, which is wanting in the other instances.

Petalody of the stamens has been met with most frequently in the following genera:

*Ranunculus! *Anemone! *Papaver! *Clematis! *Hepatica! *Ficaria! Thalictrum. *Caltha! *Trollius! *Nigella! *Aquilegia! *Delphinium! *Adonis! *Paeonia! *Nelumbium! *Nymphaea! *Berberis! *Papaver! *Chelidonium! Sanguinaria. Podophyllum. *Mathiola! *Cheiranthus! *Iberis! *Cardamine! *Hesperis. *Barbarea! *Sinapis! *Brassica! *Helianthemum! *Viola! *Dianthus! *Saponaria! *Lychnis! *Silene! *Sagina! *Hibiscus! *Althaea! *Malva! AEsculus! *Geranium! *Pelargonium. *Tropaeolum! Oxalis! *Impatiens! *Camellia! Thea! Trifolium! Medicago! *Ulex! Spartianthus. Clitoria. Pisum! Orobus! Genista! Spartium! Cytisus! Anthyllis. Coronilla. Lotus! *Rosa! *Kerria! *Spiraea! *Fragaria! *Potentilla! *Crataegus! Cydonia. *Pyrus! Eriobotrya! *Amygdalus! *Prunus! *Myrtus! *Punica! *Philadelphus! *Deutzia! *Fuchsia! Godetia! Clarkia! Portulaca! Ribes! Saxifraga! Daucus. Ixora. Serissa! Gardenia! Lonicera! Sambucus. Viburnum. Scabiosa. *Campanula! Platycodon! Calluna! Azalea! Rhododendron! *Arbutus! *Erica! *Anagallis! *Primula! *Jasminum! Syringa! *Vinca! *Nerium! Allamanda! Tabernaemontana. *Calystegia! Convolvulus! Ipomoea. *Datura! *Petunia! Solanum! Orobanche. Gentiana. Mimulus. *Antirrhinum! Gratiola! *Digitalis! *Linaria! Veronica! Calceolaria! Achimenes. Gloxinia! Clerodendron! Bignonia. Cyclamen! Mirabilis. Laurus! Gladiolus! Crocus! Iris! *Galanthus! Leucojum! Sternbergia! Hippeastrum. *Narcissus! *Orchis! Catasetum! Hydrocharis. Asphodelus. *Tulipa! Scilla. *Convallaria! Fritillaria! *Lilium! *Hyacinthus! *Polianthes! *Hemerocallis! *Colchicum! *Sagittaria! *Tradescantia! Commelyna! Tofieldia.

Petalody of the pistils.—Taken by itself, this is much less common than the corresponding change in the stamens. It generally affects the style and stigma only, as happens normally in Petalostylis, Iris, &c., but this is by no means always necessarily the case. In some of the cultivated varieties of Anemone and Ranunculus all the parts of the flower remain in their normal state, except the pistils, which latter assume a petaloid appearance.

Many of the double flowers owe their peculiar appearance to the combination of the following appearances—a petal-like form of the stamens, increase in the number of these organs and similar changes affecting the pistils, and is applied to several distinct conditions. If in any given flower all the stamens and all the pistils become wholly petaloid, no pollen is formed, and of course no seeds can be produced, but this very rarely happens, as usually some pollen is produced, and some ovules capable of being fertilised are developed.

In double flowers of Primula sinensis it frequently happens that the capsule is either partially leafy or partly petal-like; in either case the fruit is open at the extremity, and often destitute of the style and stigma. It is, however, doubtful if the ovules can be fertilised in these flowers.

The following list comprises the names of those genera in which this change has been most frequently observed, independently of corresponding alterations in the stamens, but it is more usual for both sets of organs to be similarly affected.

*Ranunculus! *Anemone! Nigella. *Papaver! *Dianthus! Saponaria! Viola! Camellia! Alcea. Hibiscus! Amygdalus! Lonicera! Scabiosa. AEschynanthus! Primula!

Petalody of the ovules.—The principal changes which occur in the ovule have already been alluded to at pp. 262-272; it may here be stated, however, that the ovules are occasionally represented by small stalked petal-like structures. This happens with especial frequency among Cruciferae.[313]

Petalody of the accessory organs.—A petaloid condition of the disc, of the scales, or other excrescences from the axis or from the lateral portions of the flower, is of frequent occurrence, though it is but rarely that the change is of any great importance in a morphological point of view. C. Morren has given the name adenopetaly to a case wherein one of the glands at the base of the petals in Lopezia was replaced by a petal.[314] A similar change may be seen in the double Oleander.

Staminody of the bracts.—An instance of this has been already alluded to in Abies excelsa, as observed by Prof. Dickson, and in which some of the bracts were seen assuming the form and characteristic of the stamens see ante: p. 192. Signor Licopoli met with a similar substitution of anthers for bracts in Melianthus major.[315]

Staminody of the sepals and petals.—In the first named this is of very rare occurrence. M. Gris has recorded an instance in Philadelphus speciosus[316] which appears to be the only case on record. The corresponding change in the case of the petals is far more common. De Candolle cites in illustration of this occurrence flowers of the common haricot, in which the alae and carina of the corolla were thus changed.[317] There is in cultivation a form of Saxifraga granulata wherein the petals are replaced by stamens, so that there are fifteen stamens. A similar change has been observed in Capsella bursa-pastoris.

Cramer figures and describes a stamen occupying the place of a petal in Daucus Carota.[318] Turpin[319] describes a similar occurrence in Monarda fistulosa, in which the lower lip terminated in an anther, but this may have been a case of adhesion. Moquin cites from Chamisso, Digitalis purpurea, and from Jussieu, Asphodelus ramosus, as having presented this change, and Wiegmann[320] has seen anthers developed on the awns of Avena chinensis. In semi-double flowers of Ophrys aranifera and Orchis mascula, the lateral petals are occasionally partially antheroid, and others occur in which two of the outer series of stamens, which are ordinarily suppressed, are present, but in a petaloid state. Reichenbach[321] figures an illustration of this change, and also Moggridge.[322]

Staminody of the pistils.—The existence of this change has been denied by several authors, nevertheless, it is of sufficiently common occurrence. Alexander Braun notices the transformation of pistils into stamens in Chives (Allium Scorodoprasum), and in which three stamens appeared in the place of as many pistils, and had extrorse anthers, while the six normal anthers are introrse. In the horse-radish (Armoracia rusticana), two of the carpels are frequently converted into stamens, while two other organs absent from the normal flower make their appearance as carpels. Roeper has observed this phenomenon in Euphorbia palustris,[323] and in Gentiana campestris.[324] In these examples one of the carpels was apparently absent, and its place supplied by an anther. Roeper has also mentioned a balsam with a supernumerary stamen occupying exactly the position of a carpel.[325]

Agardh has observed a similar thing in a hyacinth, one half of the fruit of which contained seeds, and the other half, anthers. B. Clarke mentions an instance in Mathiola incana in which the carpels were disunited, and antheriferous at the margin.[326]

The passage of pistils to stamens in willows has been frequently remarked, as in Salix babylonica, silesiaca, cinerea, Caprea and nigricans. One of the most curious illustrations of this transformation in this genus is given by Henry and Macquart (Erst. Jahrb. des bot. Vereines am m. et n. Rhein., 1837). In the flowers in question the series of changes were as follows:—first, the ovary opened by a slit, and then expanded into a cup; next, anther-cells were developed on the margin of the cup, with stigmas alternating with them, the ovules at the same time disappearing; lastly, the margin became divided, and bore three perfect anthers, which in the more perfect states were raised on three filaments.

Campanula persicifolia, C. rapunculoides, and C. glomerata have been observed to present an anther surmounting the pistil.[327] Double tulips often present this change, and a like appearance has been observed in Galanthus nivalis, and Narcissus Tazetta.

Moquin mentions the existence of this condition in a female plant of maize, some of the pistils of which were wholly or partially converted into anther-like organs. Mohl has recorded an analogous malformation in Chamaerops humilis, and in which the three carpels were normally formed, and only differed from natural ovaries in this, that along the two edges of the ventral suture there was a yellow thickening, which a cross section of the ovary showed to be an anther-lobe filled with pollen.[328]

In Tofieldia calyculata a similar substitution of a stamen for a carpel has been observed by Klotsch,[329] and Weber[330] gives other instances in Prunus and Paeonia. Corresponding alterations may be met with in cultivated tulips, in the cowslip and other plants. In most of the above cases the transmutation has been perfect, but in quite an equal number of cases a portion only of the carpel is thus changed, generally the style or the stigma; thus Baillon describes the stigmas of Ricinus communis as having been in one instance antheriferous.[331] Moggridge figures a flower of Ophrys insectifera in which the rostellate process was replaced by an anther.[332]

Mohl remarks that the change of pistils into stamens is more common in monocarpellary pistils than it is in those which are made up of several carpels. It seems clear that in this transformation the lobes of the anther and the development of pollen have no relation to the production of ovules.

Staminody of the accessory organs of the flower.—The scales that are met with in some plants, either as excrescences from the petals, or as imperfect representatives of stamens or other organs, are occasionally staminoid; thus the scales of Saponaria officinalis, of Silene, Nerium Oleander, the rays of Passiflora, the corona of Narcissus, have all been observed occasionally to bear anthers.[333] In the case of Narcissus the loose spongy tissue of the corona seems to have the nearest analogy to the anther-lobes, while the prolonged connective is more like the ordinary segments of the perianth in texture. The species in which this change may most frequently be observed are, N. poeticus, N. incomparabilis, and N. montanus.

M. Bureau found in some flowers of Antirrhinum majus two petal-like bodies standing up in front of, or opposite to the two petals of the upper lip,[334] and similar developments in which each of the two adventitious segments are surmounted by an anther may be met with frequently. It does not follow because these organs bear anthers that they are morphologically true stamens. They are really scales, &c., taking on themselves accidentally the characters proper to stamens.

Pistillody of the perianth.—The passage of the segments of the perianth into carpels has been observed frequently in Tulipa Gesneriana, the change in question being generally attended by a partial virescence. M. Gay is said by Moquin to have observed a flower of Crocus nudiflorus in which the segments of the perianth were cleft and fringed at the same time, so that they presented the appearance of the stigmas.



Pistillody of the sepals.—In some double flowers of the garden pea communicated by Mr. Laxton, among other peculiarities was a supernumerary 5-6-leaved calyx, some of the segments of which were of a carpellary nature, and bore imperfect ovules on their margins, while at their extremities they were drawn out into styles.[335]

Pistillody of the stamens.—This change whereby the stamens assume more or less the appearance of pistils is more commonly met with than is the metamorphosis of the envelopes of the flower into carpels. In some cases the whole of the stamen appears to be changed, while in others it is the filament alone that is altered, the anther being deficient, or rudimentary; while, in a third class of cases, the filament is unaffected, and the anther undergoes the change in question. In those instances in which the filament appears to be the portion most implicated, it becomes dilated so as to resemble a leaf-sheath rather than a leaf-stalk, as it does usually.

One of the most curious cases of this kind is that recorded in the 'Botanical Magazine,' (tab. 5160, f. 4) as having occurred in Begonia frigida already alluded to, and in which, in the centre of a male flower, were four free ovoid ovaries alternating with as many stamens. In the normal flowers of this plant, as is well known, the male flowers have several stamens, while in the female flowers the ovary is strictly inferior, so that, in the singular flower just described, the perianth was inferior instead of being superior, as it is usually. It should be added also that the perianth in these malformed flowers was precisely like that which occurs ordinarily in the male flowers.



In some varieties of the orange, called by the French "bigarades cornues," the thalamus of the flower, which is usually short, and terminated by a glandular ring-like disc, is prolonged into a little stalk or gynophore, bearing a ring of supernumerary carpels. These carpels are isolated one from another, and are formed by the transformation of the filaments of the stamens.[336]

The additional carpels in the case of the apple of St. Valery, in which the petals are of a green colour, like the sepals, are by some attributed to the transformation of the stamens into carpels. These adventitious carpels frequently contain imperfect ovules and form a whorl above the normal ones. (See Pyrus dioica of Willdenow.)[337] A similar change occasionally happens in the stamens of Magnolia fuscata, while in double tulips this phenomenon is very frequent, and among them may be found all stages of transition between stamens and pistils, and many of the parts combining the characters of both.[338] Dunal and Campdera have described flowers of Rumex crispus, with seven pistils, occupying the place of as many stamens.



In Papaver bracteatum a considerable number of the stamens sometimes become developed into pistils, especially those which are nearest to the centre of the flower, and in these flowers the filaments are said to become the ovaries, while the anthers are curled so as to resemble stigmas. A similar change is not infrequent Papaver somniferum. Goeppert, who found numerous instances of the kind in a field near Breslau, says the peculiarity was reproduced by seed for two years in succession.[339] Wigand ('Flora,' 1856, p. 717) has noticed among other changes the pistil of Gentiana Amarella bearing two sessile anthers. Polemonium caeruleum is another plant very subject to this change. Brongniart[340] describes a flower of this species in which the stamens were represented by a circle of carpels united to each other so as to form a sheath around the central ovary. By artificial fertilization M. Brongniart obtained fertile seeds from the central normal ovary as well as from the surrounding metamorphosed stamens.

Cheiranthus Cheiri has long been known as one of the plants most subject to this anomaly. De Candolle even mentions it in his 'Prodromus' as a distinct variety, under the name of gynantherus. Brongniart (loc. cit.) thus refers to the Cheiranthus:—"Sometimes these six carpellary leaves are perfectly free, and in this case they spread open, presenting two rows of ovules along their inner edges, or these edges maybe soldered together, forming a kind of follicle like that of the columbine; at other times, these staminal pistils are fused into two lateral bundles of three in each bundle, or into a single cylinder which encircles the true pistil. In a third set of cases these outer carpels are only four in number, two lateral and two antero-posterior, all fused in such a manner as to form around the normal pistil a prism-shaped sheath, with four sides presenting four parietal placentae, corresponding to the lines of junction of the staminal carpels."

In the accompanying figures (fig. 163, a-d) the nature of this change is illustrated. In some of the specimens it is easy to see that the two shorter stamens undergo the change into carpels later and less perfectly than the four longer ones, and not infrequently the outer pair are altogether absent. In most of the flowers of this variety the petals are smaller and less perfectly developed than usual.[341]



In Lilium tigrinum, some specimens of which were gathered by Mr. J. Salter, in addition to various degrees of synanthy and other changes, some of the stamens were developed in the form of carpels, adherent by their edges so as to form an imperfect tube or sheath around the normal pistil. Fig. 164 shows one of the intermediate organs from these flowers, in which half the structure seems devoted to the formation of ovules, while the other half bears a one-celled anther. Lindley[342] has also described a case of this kind in a species of Amaryllis.



In Saxifraga crassifolia it sometimes happens that mixed with the stamens, and originating with them, are a number of distinct and perfectly formed carpels, wholly separated from the normal carpels, in the centre of the flower. In this particular instance there is usually no intermediate condition between the stamen and the pistil. Guillemin[343] also describes a transformation of the stamens into carpels in Euphorbia esula.

When the anther is involved it may be only partially so, or almost the whole organ may be transformed. As instances of very partial change may be cited the passage of the connective into a stigma in Thalictrum minus, or the passage of the points of the anthers into imperfect styles in some species of bamboo.[344]

In Rosa arvensis similar transformations have been observed of a slightly more complex character than those just mentioned, and passing into more important changes, especially to the formation of pollen within ovules, formed on the edges of an open carpellodic anther (see p. 186).

Mr. Berkeley has recorded an analogous case in a gourd in which the stamens bore numerous ovules (p. 200), and Baillon describes another gourd in which certain fleshy appendages surrounding the androecium were provided with ovules.[345]

Payer, in his 'Organogenie,' p. 38, mentions a stamen of Dionaea bearing not only an anther, but likewise an ovule.

Sempervivum tectorum and S. montanum, have long been noticed as being very prone to present this change. Mohl[346] remarks that, in the transformation of the stamens to the pistil in the common houseleek, the filament of the stamen generally preserves its form, the anthers alone undergoing change. At other times, however, the transformation takes place at the same time, both in the filament and in the anther. When the stamens are numerous some of them remain in their normal state, while others, and especially the inner ones, undergo a change. Sometimes all the stamens are changed simultaneously, while at other times some of these organs may be found in which the anther is partially filled with ovules, and partially with pollen.

In the accompanying figures (fig. 165, a-h) a series of intermediate stages is shown between the ordinary stamen of Sempervivum tectorum and the ordinary carpel, from which it will be seen that the filament is little, if at all, affected, and that in those cases where there is a combination of the attributes of the stamen and of the pistil in the same organ the pollen is formed in the upper or inner surface of the leaf-organ, while the ovules arise from the opposite surface from the free edge, (b, c, d, e, f, g).

In a drawing made by the Rev. G. E. Smith of a malformed flower of Primula acaulis, and which the writer has had the opportunity of examining, the stamens are represented as detached from the corolla, and their anthers replaced by open carpels, with ovules arising, not only from their edges, but also from their surfaces, while the apex of the carpellary leaf was drawn out into a long style, terminated by a flattened spathulate stigma.

Delphinium elatum is one of the plants in which this change has been most frequently noticed.[347]



In willows the change of pistils into staminal organs has been frequently observed. In Salix babylonica Prof. Schnizlein has described various transition stages between the carpels and the stamens, and in one instance, in addition to this change, a perfect cup-shaped perianth was present, as happens normally in Populus[348]. Mr. Lowe also records the conversion of stamens into ovaries in Salix Andersoniana, and this by every conceivable intermediate gradation.[349]

The following list will serve to show what plants are most subject to this anomaly. It is difficult to draw any accurate inference from this enumeration, but attention may be called to the frequency of this occurrence in certain plants, such as the Sempervivum, the wallflower, the poppy, and the heath. Why these plants should specially be subject to these changes cannot be at present stated.

By the student of animal physiology such a change as above described—equivalent to the substitution of an ovary or a uterus for a testis—would be looked on as next to impossible; the simpler and less specialised structure of plants renders such a change in them far more easy of comprehension.

Thalictrum minus. Delphinium elatum. Magnolia fuscata. Bocconia cordata. *Papaver bracteatum! * somniferum! nudicaule. Dionaea muscipula! Barbarea vulgaris. *Cheiranthus Cheiri! Cochlearia Armoracia. Tropaeolum majus. Citrus Aurantium. *Sempervivum tectorum! montanum. Begonia frigida! Cucumis, sp. Cucurbita Pepo. Pyrus Malus. Rosa arvensis! Saxifraga crassifolia! Myrtus, sp. Campanula rapunculoides. Polemonium caeruleum. Gentiana Amarella. *Erica Tetralix. Stachys germanica. Primula acaulis. Rumex crispus. *Salix, sp. plur.! Euphorbia esula. Glochidion. Asphodelus ramosus. Amaryllis. Lilium tigrinum! longiflorum. *Tulipa Gesneriana! var. cult. plurim.! Hemerocallis. Zea Mays. Bambusa, sp.

Pistillody of the ovule.—An instance of this extraordinary transformation in the carnation, as observed by the Rev. Mr. Berkeley, is given at p. 268.

FOOTNOTES:

[295] 'Neue Denkschrift. Schweiz. Gesellsch.,' band v, p. 9.

[296] 'Bull. Acad. Belg.,' xix, part 2, p. 93.

[297] Schlechtendal, 'Linnaea,' ix, p. 737.

[298] Misbilld., 'Cult. Gewachs.,' p. 32.

[299] Linn., 'Phil. Botan.,' Sec. 120.

[300] 'Bull. Soc. Bot. France,' 1859, vol. vi, p. 199.

[301] Seemann's 'Journal of Botany,' vol. iii, p. 105; also Morren, 'Bull. Acad. Belg.,' vol. xx, part 2, p. 264.

[302] Morren, 'Bull. Belg.,' xviii, p. 503.

[303] 'Organ. Veg.,' t. i, p. 513.

[304] 'Bull. Acad. Roy. Belg.,' tome xvii; and Lobelia, p. 65.

[305] Masters, "On Double Flowers," 'Rep. Internat. Bot. Congress,' London, 1866. p. 127.

[306] See also C. Morren, "Sur les vraies fleurs doubles chez les Orchidees," 'Bull. Acad. Roy. Belg.,' vol. xix, part ii, 1852. p. 171.

[307] C. Morren, 'Bull. Acad. Belg.,' vol. xx, 1853, part ii, p. 284 (Syringa).

[308] 'Rep. Bot. Congress,' London, 1866, p. 135, t. vii, f. 14.

[309] Although it is generally admitted that the filament of the stamen corresponds to the stalk of the leaf, and the anther to the leaf-blade, yet there are some points on which uncertainty still rests. One of these is as to the sutures of the anther. Do these chinks through which the pollen escapes correspond (as would at first sight seem probable) to the margins of the antheral leaf, or do they answer to the lines that separate the two pollen-cavities on each half of the anther one from the other? Professor Oliver, 'Trans. Linn. Soc.,' vol. xxiii, 1862, p. 423, in alluding to the views held by others on this subject, concludes, from an examination of some geranium flowers in which the stamens were more or less petaloid, that Bischoff's notion as to the sutures of the anther is correct, viz., that they are the equivalents of the septa of untransformed tissue between the pollen-sacs. Some double fuchsias ('Gard. Chron.,' 1863, p. 989) add confirmation to this opinion. In these flowers the petals were present as usual, but the stamens were more or less petaloid, the filaments were unchanged, but the anthers existed in the form of a petal-like cup from the centre of which projected two imperfect pollen-lobes (the other two lobes being petaloid). Now, in this case, the margins of the anther were coherent to form the cup, and the pollen was emitted along a line separating the polliniferous from the petaloid portion of the anther. This view is also borne out by the double-flowered Arbutus Unedo, and also by what occurs in some double violets, wherein the anther exists in the guise of a broad lancet-shaped expansion, from the surface of which project four plates (fig. 157), representing apparently the walls of the pollen-sacs, but destitute of pollen; the chink left between these plates corresponds thus to the suture of the normal anther.



The inner or upper portion of the anther-leaf is that which is most intimately concerned in the formation of pollen; it comparatively rarely (query ever) happens that the back or lower surface of the antheral leaf is specially devoted to the formation of pollen. On the other hand, in cases like those of the common houseleek, where we meet with petaloid organs combining the attributes of anthers and of carpels, we find the inner layers devoted to the production of pollen, the outer to the formation of ovules.

That the pollen-lobes are not to be taken as halves of a staminal leaf, but rather as specialised portions of it, not necessarily occupying half its surface, is shown also in the case of double-flowered Malvaceae, in which the stamens are frequently partly petal-like, partly divided into numerous separate filaments, each bearing a one-, or it may be even a two-lobed anther. This circumstance is confirmatory of the opinion held by Payer, Duchartre, Dickson, and other organogenists, as to the compound nature of the stamens in these plants. The stamens are here analogues not of a simple entire leaf, but of a lobed, digitate, or compound leaf, each subdivision bearing its separate anther. On this subject the reader may consult M. Mueller's paper on the anther of Jatropha Pohliana, &c., referred to at page 255.

[310] See C. Morren, "On Spur-shaped Nectarines," &c., 'Ann. Nat. Hist.,' March, 1841, p. 1. tab. 11.

[311] Karsten, 'Flor. Columb. Spec.,' tab. xxix.

[312] See Dickson, "On Diplostemonous Flowers," 'Trans. Bot. Soc. Edin.,' vol. viii, p. 100; and on the Androecium of Mentzelia, &c., in Seemann's 'Journal of Botany,' vol. iii, p. 209, and vol. iv (1866) p. 273 (Potentilla, &c.).

[313] See Baillon, 'Adansonia,' iii, p. 351, tab. 12, Sinapis.

[314] 'Bull. Acad. Belg.,' xvii, part i, p. 516, c. tab., and 'Lobelia,' p. 83.

[315] Cited in 'Bull. Soc. Bot. France,' xiv, p. 253 ('Rev. Bibl.').

[316] 'Bull. Soc. Bot. Fr.,' 1858, p. 331.

[317] 'Mem. Legum.,' p. 44.

[318] 'Bildungsabweich, 'Pflanz. Fam.,' tab. 8, f. 12.

[319] 'Atlas de Goethe' p. 55, t. 4, f. 18.

[320] Wiegmann, 'Bot. Zeit.,' 1831, p. 5, tab. i.

[321] 'Ic. Flor. Germ.,' xiii, tab. 112, cccclxiv, f. 2.

[322] Seemann's 'Journal of Botany,' 1867, p. 317, t. 72, A (Ophrys).

[323] 'Enum. Euphorb.' p. 53.

[324] 'Linnaea.' i, p. 457.

[325] 'De Balsam,' p. 17.

[326] B. Clarke, 'Arrangement of Phaenog. Plants,' p. 23.

[327] See 'Engelmann,' p. 26, tab. 3, f. 10, 11, 14.

[328] 'Ann. Sc. Nat.,' ser. 2, t. viii, 1837, p. 58.

[329] 'Bot. Zeit.,' 4, 1846, 889.

[330] 'Verhandl. Nat. Hist. Ver. Preuss. Rheinl. und Westph.,' 1858, 1860, p. 381. Cramer also, 'Bildungsabweich,' p. 90, cites a case in Paeonia where the carpel was open and petaloid, and bore an anther on one margin, and four ovules on the other.

[331] 'Euphorbiaceae,' p. 205.

[332] Seemann's 'Journ. Bot.,' iv, p. 168, tab. 47, f. 1.

[333] Moquin-Tandon, l. c., 220, Passiflora. Masters, 'Journ. Linn. Soc.,' 1857, p. 159, Saponaria. Seemann's 'Journ. Botany,' vol. iii, p. 107, Narcissus.

[334] 'Bull. Soc. Bot. Fr.,' 1857, p. 452.

[335] 'Gardeners' Chronicle,' 1866, p. 897.

[336] Maout, 'Lecons Element.,' vol. ii, p. 488.

[337] Poiteau and Turpin, 'Arb. Fruit,' t. 37, and Trecul, 'Bull Soc. Bot. France,' vol. i. p. 307.

[338] Clos, 'Mem. Acad. Toulouse,' 5 ser., vol. iii.

[339] 'Bot. Zeit.,' 1850, t. viii, pp. 514, 664. 'Flora,' (B. Z.) 1832, t. xv, p. 252; also cited in 'Ann. des Serres et des jardins,' vi, pp. 241-5. See also Schlechtendal, 'Bot. Zeit.,' 1845, t. 3, p. 6.

[340] 'Bull. Soc. Bot. France,' t. viii, p. 453.

[341] See also Allmann, 'Rep. Brit. Assoc.,' July, 1851.

[342] 'Theory of Horticulture,' ed. 2, p. 82.

[343] 'Mem. Soc. Hist. Nat. Paris.' i, 16.

[344] Gen. Munro, 'Trans. Linn. Soc.,' xxvii, p. 7.

[345] 'Bull. Soc. Bot. Fr.,' 1857, p. 21.

[346] 'Ann. Scienc. Nat.,' t. viii, 1837, p. 50, and 'Bot. Zeit.' (R.), 1836, t. xix, p. 513, &c. See also MM. Sourd Dussiples and G. Bergeron, 'Bull. Soc. Bot. France,' viii, p. 349; Von Schmidel, 'Icon. plant. et Anal. part.' 1782, p. 210, fig. 54.

[347] Godron, 'Bull. Soc. Bot. Fr.,' xiii, p. 82, Rev. Bibl.

[348] Cited in Henfrey, 'Bot. Gazette,' iii, p. 12.

[349] 'Ann. Nat. Hist.,' September, 1856, p. 56. See also Kirschleger, 'Flora (Bot. Zeit.),' xxiv, 1841, p. 340, Salix alba. Henschel, 'Flora (Bot. Zeit.),' 1832, t. xv, p. 253, S. cinerea. Hartmann, 'Flora (Bot. Zeit.),' xxiv, p. 199, S. nigricans. Meyer, C. A., 'Bull. Phys. Math.,' t. x, S. alba.



PART IV.

HETEROMORPHY.

There are certain malformations that have little in common beyond this, that they cannot readily be allocated in either of the great groups proposed by writers on teratology. There are also deformities which, unlike the majority of deviations from the ordinary structure, are absolute and not relative. While the latter are due to an exaggeration, or to an imperfection of development, or, it may be, to a partial perversion in organization, the former differ from the normal standard, not merely in degree, but absolutely. This is often the case when disease or injury affects the plant; for instance, in the case of galls arising from insect-puncture the structure is rather a new growth altogether, than dependent on mere hypertrophy of the original tissues. These absolute deformities arising from the causes just mentioned belong rather to pathology than to teratology strictly so called; but, under the head of deformities, may be mentioned sundry deviations not elsewhere alluded to.



CHAPTER I.

DEFORMITIES.

The special meaning here attached to the term deformity is sufficiently explained in the preceding paragraph; it remains to give a few illustrations, and to refer to other headings, such as Heterotaxy, Hypertrophy, Atrophy, &c., for malformations capable of more rigid classification than those here alluded to.



Formation of tubes.—The production of ascidia or pitchers from the cohesion of the margins of one or more leaves has been already alluded to (see pp. 21, 30), but there is another class of cases in which the tubular formation is due, not so much to the union of the margins of a leaf as to the disproportionate growth of some portions as contrasted with others, whence arises either a depressed cavity, as in the case of a leaf, or an expanded and excavated structure, when the stem or some portion of it is affected.

The fruit of the rose, the apple, the fig, and many others, is now generally admitted to be composed externally of the dilated end of the flower-stalk in which the true carpels become imbedded. Between such cases and that of a peltate leaf with a depressed centre, such as often occurs, to some extent, in Nelumbium, there is but little difference.

In cabbages and lettuces there not unfrequently occurs a production of leaf-like processes projecting from the primary blade at a right angle (see Enation). Sometimes these are developed in a tubular form, so as to form a series of little horn-like tubes, or shallow troughs, as in Aristolochia sipho. At other times the nerves or ribs of the leaf project beyond the blade, and bear at their extremities structures similar to those just described.



In a variety of Codiaeum variegatum a similar formation may be seen to a minor extent. Even the common Scolopendrium vulgare occasionally produces small pitchers of this character, as in the varieties named perafero-corautum, Moore, and peraferum, Woll.[350]

In carnations leaves may sometimes be seen from both surfaces, from which project long, sharp-pointed tubular spurs at irregular intervals. A very singular illustration of this is figured by Trattinick,[351], in which the leaves, epicalyx, sepals, and petals, were all provided with tubular spurs.

In Cephalotus follicularis rudimentary or imperfect pitchers may be frequently met with, in which the stalk of the leaf is tubular and bears at its extremity a very small rudimentary leaf-blade. It is not in all cases easy to trace the origin and true nature of the ascidium, as the venation is sometimes obscure. If there be a single well-marked midrib the probability is that the case is one of cohesion of the margins of the leaf; but if the veins are all of about equal size, and radiate from a common stalk, the pouch-like formation is probably due to dilatation and hollowing of the petiole. Again, when the result of a union of the margins of the leaf, the pitcher is generally less regular than when formed from the hollowed end of a leaf-stalk. Further information is especially needed as to the mode of development and formation of these tubular organs, so as to ascertain clearly when they are the result of a true cupping process, and when of cohesion of the margins of one or more leaves. (See Cohesion, p. 31. For bibliographical references consult also A. Braun, 'Flora v. Bot. Zeit.,' 1835, t. xviii, p. 41, Aristolochia.)

Tubular formations in the flower.—A similar formation of tubes happens in some double flowers; for instance, it is not infrequent in double flowers of Primula sinensis, in which tubular petal-like structures are attached to the inner surface of the corolla; sometimes these petaloid tubes replace the stamens, while at other times they appear to have no relation to those organs. In the particular flowers now alluded to the tubular form seems due to a dilatation, and not to a cohesion of the margins. (See Cohesion, p. 23.) These tubular petals resemble in form and colour almost precisely the normal corolla in miniature, but are not surrounded by a calyx, nor do they contain stamens, while the less perfect forms show clearly their origin from a single tube-like organ.



The formation of spurs or spur-like tubes in a quasi-regular manner has been spoken of under the head of Irregular Peloria, p. 228, but we occasionally meet with tubular processes which seem to occur in an irregular manner, and to have no reference to the symmetrical plan of the flower, and which are due probably to the same causes as those which induce hypertrophy. Such spurs have frequently been seen on the corolla of Digitalis purpurea, Antirrhinum majus,[352] Tulipa Gesneriana, and occasionally on the sepals of Fuchsia. They are very frequent in some seasons in the corolla of certain calceolarias (C. floribunda). By Morren this production of adventitious spurs was called "Ceratomanie."



Similar processes may sometimes be seen in the capsules of Linaria vulgaris, as also in the fruits of some of the Solanums, quite without reference to the arrangement of the carpels, so that their production seems to be purely irregular.

Morren, as previously remarked, gave the name "Solenaidie" to tubular deformities affecting the stamens, a term which has not been generally adopted; the deformity in question is by no means of uncommon occurrence in some double or partially pelorised flowers, as Antirrhinum, Linaria, &c. A similar formation of conical out-growths may frequently be met with in the fruits quite irrespectively of any disjunction of the carpels.

Contortion.—An irregular twisting or bending of the stem or branches is by no means of uncommon occurrence, the inducing causes being often some restriction to growth in certain directions, or the undue or disproportionate growth in one direction, as contrasted with that in another. Hence it may arise from insect-puncture, parasitic growth, or any obstacle to the natural development. Frequently it exists in conjunction with fasciation, the ends of the branches being curved round like a shepherd's crook, from the growth on one side being so much greater than on the other. Sometimes it is a mere exaggeration of a normal condition; thus, in what are termed flexuose stems the stem twists alternately to one side or another, frequently in association with an oblique form of the leaf. This state is sometimes present to an extreme degree, as in some varieties of shrubs (Crataegus, Robinia, &c.) cultivated for their singularly tortuous branches.



Such cases as those just mentioned, however, are but slightly irregular compared to others in which the deformity exists to such an extent that the traces of the ordinary mode of growth are almost obliterated. M. Moquin-Tandon[353] alludes to a case of this kind in a species of pine (Pinus), in which a branch ended in four unequal divisions, which were strongly curved from without inwards, then became united in pairs, these latter in their turn blending into a single mass.

In the case of some beeches growing in the forest of Verzy, near Rheims, the trunks of the trees are contorted in every direction, and, at a height of from fifteen to twenty feet, a number of branches are also given off, also much contorted, and occasionally intergrafted, so that it seems as if a heavy weight had been placed on the trees and literally flattened them. Similar malformations may occasionally be met with in the branches of the oak, and commonly in the weeping ash.

M. Fournier[354] mentions the stems of Ruscus aculeatus rolled in a circle, others twisted spirally.

The phenomenon is not confined to woody plants, but has been met with in chicory, in Antirrhinum, and other herbaceous species.

It is very difficult in some cases to separate these instances of irregular torsion from those in which the twisting takes place in a more or less regular spiral direction. In the former case the fibres of the plant are only indirectly involved, but in the latter the fibres themselves are coiled spirally from right to left, or vice versa (spiral torsion), while not unfrequently both conditions may be met with at the same time.

The leaves also are subject to similar deformities, of which a notable illustration has been recorded in the case of the date palm, Phoenix dactylifera, originally observed by Goethe, and figured and described by Jaeger;[355] the leaves are folded and twisted in every direction, in consequence of the fibrous band or cord which surrounds the leaves, and which generally breaks as the leaflets increase in size, remaining from some cause or other unbroken, and thus serving to restrain the growth.

A similar irregularity of growth occurs, not unfrequently, in the case of crocus leaves, when in the course of their growth, as they push their way through the soil, their progress becomes checked either by a stone or even by frost.

Spiral torsion.—Growth in a spiral direction, and the arrangement of the various organs of the plant in a spiral manner, are among the most common of natural phenomena in plants.[356] Fibres are coiled spirally in the minute vessels of flowering plants, and are not wholly wanting even among fungi. The leaf-organs are very generally spirally arranged; the leaf-stalks are often so twisted as to bring leaves on one plane which otherwise would occupy several. In the leaf itself we have a spiral twist taking place constantly in Alstroemeria, in Avena, and other plants. A similar tendency is manifested in the flower-stalks, as in Cyclamen and Vallisneria, and the whole inflorescence, as in Spiranthes. Even the bark and wood of trees is often disposed spirally. This is very noticeable in some firs, and in the bark of the sweet chestnut (Castanea), of Thuja occidentalis, and other trees. The knaurs or excrescences which are sometimes found on the roots or stems of trees afford other illustrations of this universal tendency. These bodies consist of a number of embryo buds, which, from some cause or other, are incapable of lengthening. On examination every rudimentary or undeveloped bud may be seen to be surrounded by densely crowded fibres arranged spirally.

The axes of nearly all twining plants are themselves twisted, and twisted in a direction corresponding to the spontaneous revolving movement exhibited by these plants, as in the hop, the convolvulus, passion flower, &c., the degree of twisting being dependent to a great extent on the roughness of the surface around which the stem twines[357].

Considered as an exceptional occurrence, it occurs frequently in certain plants, and, when it affects the stem or branches, necessarily causes some changes in the arrangement of the parts attached to them; thus, spiral torsion of the axial organs is generally accompanied by displacement of the leaves, whorled leaves becoming alternate, and opposite or whorled leaves becoming arranged on one side of the stem only. Frequently also this condition is associated with fasciation, or, at least, with a distended or dilated state. An illustration of this in Asparagus has been figured at p. 14.

Very often the leaves are produced in a spiral line round the stem, as in a specimen of Dracocephalum speciosum described and figured by C. Morren. The leaves of this plant are naturally rectiserial and decussate, but, in the twisted stem the leaves were curviserial, and arranged according to the 5/13 plan. Now, referring to the ordinary notation of alternate leaves, we shall have the first leaf covered by the fifth, with two turns of the spiral; since decussate leaves result from two conjugate lines, the formula will be necessarily 2/5. The fraction 5/13 hence comes regularly into the 2/5 series (2/5, 3/8, 5/13). Thus, the leaves in assuming a new phyllotaxy, take one quite analogous to the normal one.

One of the most curious instances that have fallen under the writer's own observation occurred in the stem of Dipsacus fullonum. (See 'Proceedings of the Linnean Society,' March 6, 1855, vol. ii, p. 370). The stem was distended, and hollow, and twisted on itself; its fibres, moreover, were arranged in an oblique or spiral direction; the branches or leaf-stalks, which usually are arranged in an opposite and decussate manner, were, in this case, disposed in a linear series, one over the other, following the line of curvature of the stem. When the course of the fibres was traced from the base of one of the stalks, upward around the stem, a spiral was found to be completed at the base of the second stalk, above that which was made the starting point. Now, if opposite leaves depend on the shortened condition of the internode between the two leaves, then, in the teazel-stem just described, each turn of the spiral would represent a lengthened internode; and, if the fibres of this specimen could be untwisted, and made to assume the vertical direction, and, at the same time, the internodes were shortened, the result would be the opposition of the branches and the decussation of the pairs; this explanation is borne out by the similar twisting which takes place so frequently in the species of Galium and other Rubiaceae.



G. Franc[358] was one of the first to notice this twisting in Galium, and M. Duchartre,[359] in mentioning a similar instance, gives the following explanation of the appearance which will be found to apply to most of these cases. In the normal stem of Galium Mollugo the branches are opposite in each verticil and crossed in the two successive ones. The stem is four-angled, each angle having a nerve. Each of these nerves, springing from the origin of a branch in one whorl, terminates in the interval which separates the point of origin of the two branches in the whorl next above it. In the deformed stem one of the nerves corresponds to the insertion of a branch, its neighbour is in the adjoining vacant space; hence it results that four nerves correspond to two branches and to two consecutive interspaces, and hence the analogy between a single normal internode provided with its two branches and its four nerves. What confirms this inference is that the nerve, which begins at the point of origin of a branch, after making one spiral turn round the stem, terminates in the interval that separates the two following branches, just as in a branch of the normal stem it ends in the upper whorl between the two next branches. The torsion, then, in this Galium caused the separation of the two opposite branches of the same verticil, and placed them one above another, and this being reproduced in all the whorls, all the branches come to be arranged on the same longitudinal line. The leaves are susceptible of the same explanation; they are inserted in groups of three or four in one arc round the origin of each branch. In the malformation each series or group of four leaves, with its central branch, is equivalent to half a whorl of the natural plant with its axillary branch. In other words, the malformation consists in a torsion of the stem, which separates each whorl into two distinct halves; these half-whorls, with their axillary branches, are placed on a single longitudinal series one above another. This case is quoted at some length, as it is an admirable example of a very common form of malformation in these plants.

In some parts of Holland where madder is cultivated a similar deformation is particularly frequent. The leaves, however, are not always grouped in the way in which they were described by M. Duchartre, but more commonly form a single continuous line; when arranged in leaf-whorls it generally happens that some of the leaves are turned downwards, while others are erect. It has been said that this condition occurs particularly frequently in plants growing in damp places. It is certainly true that spiral torsion of the stem is specially frequent in the species of Equisetum, most of which grow in such spots. In these plants either the whole of the upper part of the stem is thus twisted, or a portion only: thus Reinsch[360] cites a case in Equisetum Telmateia, where the upper and lower portions of the stem were normal, while the intermediate portion was twisted spirally. In this instance the whorl next beneath the spiral had twenty-eight branchlets, and that immediately above it thirty. Along the course of the spire there were two hundred and three; dividing this latter number by the mean of the two preceding, it was seen that the spire included the constituents of seven ordinary verticils.



Here also may be mentioned a curious bamboo, the stem of which is preserved in the British Museum, and in which the internodes, on the exterior, and the corresponding diaphragms and cavities within are spiral or oblique in direction.

The root is also subject to the same malformation, the inducing cause being usually some obstruction to downward growth, as when a plant has been grown in a small pot, and becomes, as gardeners say, pot-bound.



The axial portion of the flower, the thalamus, is also occasionally twisted in a spiral direction, the lateral parts of the flower being in consequence displaced. Morren spoke of this displacement of the floral organs as "speiranthie."[361]

Morren draws a distinction between spiral-torsion or spiralism and the less regular torsion spoken of in the preceding section; in the former case not only is the axis twisted, but its constituent fibres also. The condition in question in some cases seems to be inherited in the seedling plants.

The following is a list of the plants in which spiral torsion of the stem or branches has been most frequently observed. (See also under Fasciation and Contortion.)

Hesperis matronalis. Dianthus barbatus. Pyrus Malus. torminalis. Cercis siliquastrum! Punica Granatum. Robinia pseudacacia! Rubia tinctorum. Dipsacus fullonum! pilosus. Gmelini. Scabiosa arvensis. *Valeriana officinalis! dioica! Galium aparine! * Mollugo! verum! Hippuris vulgaris! Veronica spicata. longifolia. Hyssopus officinalis. Thymus Serpyllum. Lamium purpureum! Dracocephalum speciosum. Mentha aquatica. Mentha viridis. Fraxinus vulgaris! Sambucus nigra. Zinnia. Phylica. Beta. Rumex, sp. Ulmus campestris. Casuarina rigida. Abies excelsa! Lilium Martagon! candidum. *Asparagus officinalis! Sagittaria sagittifolia. Epipactis palustris. Triticum repens! Lolium perenne! Phleum pratense. Juncus conglomeratus! Scirpus lacustris. Equisetum Telmateia. limosum. fluviatile. arvense!

Among the more important papers relating to this subject may be mentioned:

Moquin-Tandon, 'El. Ter. Veg.,' p. 181. Kros, 'De Spira in plantis conspicua.' Morren, 'Bull. Acad. Roy. Belg.,' 1851, tom. xviii, part i, p. 27. Milde, 'Nov. Act. Acad. Leop. Carol. Nat. Cur., 1839. Ibid., vol. xxvi, part ii, p. 429, Equisetum. Irmisch, 'Flora,' 1858, t. ii, Equisetum. Vrolik, 'Nouv. Mem. Instit. Amsterdam,' Lilium. Schlechtendal, 'Bot. Zeit.,' xiv, p. 69, et v, p. 66. De Candolle, 'Organ. Veget., t. i, p. 155, tab. xxxvi, Mentha, &c. Alph. de Candolle, 'Neue Denkschr. Allg. Schweiz. Gesellschft.,' band v, tab. vi, Valeriana. Duchartre, 'Ann. Sc. Nat.,' ser. 3, vol. i, p. 292. 'Gardeners' Chronicle,' July 5, 1856, p. 452, c. ic. xylogr., spiral branches from Guatemala—tree not known.

Spiral twisting of the leaf is scarcely of so common occurrence as the corresponding condition in the stem. In Alstroemeria it occurs normally, as also in some grasses. In the variety annularis of Salix babylonica the leaf is constantly coiled round spirally. A similar contortion occurs in a variety of Codiaeum variegatum lately introduced from the islands of the South Seas by Mr. J. G. Veitch.

Fern fronds are occasionally found twisted in the same manner, e.g. Scolopendrium vulgare var. spirale.[362]

Adventitious tendrils.—Under ordinary circumstances tendrils may be described as modifications of the leaf, the stipule, the branch, or of the flower stalk, so that it is not a matter of surprise to find tendrils occasionally springing from the sepals or petals, as indeed happens normally in Hodgsonia, Strophanthus, &c.

M. Decaisne[363] found a flower of the melon in which one of the segments of the calyx was prolonged into a tendril, and Kirschleger records a similar instance in the cucumber, while Mr. Holland ('Science Gossip,' 1865, p. 105) mentions a case in which one of the prickles on the fruit of a cucumber had grown out into a tendril.

In Cobaea scandens the foliar nature of the tendril is shown by the occasional presence of a small leaflet on one of the branches of the tendril, and a similar appearance may frequently be seen in Eccremocarpus scaber. On the other hand, in the vine, the axial nature of the tendril is revealed by the not infrequent presence of flowers or berries on them, as also in Modecca and some Passifloraceae.

Darwin, speaking of the tendrils of Bignonia capreolata, says it is a highly remarkable fact that a leaf should be metamorphosed into a branched organ, which turns from the light, and which can, by its extremities, either crawl like a root into crevices, or seize hold of minute projecting points, these extremities subsequently forming cellular masses, which envelope by their growth the first fibres and secrete an adhesive cement.

Interrupted growth.—This term is here used in the same sense as in ordinary descriptive botany, as when an "interruptedly pinnate" leaf is spoken of. A similar alternation may be observed occasionally as a teratological occurrence, though it is not easy to account for it.



Fig. 175 shows an instance of the kind in a radish, and fig. 176 a similar deformity in the case of an apple, the dilatation of the flower-stalk below the ordinary fruit producing an appearance as if there were two fruits one above another.

In leaves this peculiar irregularity of development is more common.

In some varieties of Codiaeum variegatum the leaves resemble those of Nepenthes, as the basal portion is broad, and terminates in a projecting midrib destitute of cellular covering, and this again terminates in a small pouch or pitcher. Somewhat similar variations may be found in ferns, especially Scolopendrium vulgare.

Instead of the pouch there is formed sometimes in the plant last mentioned a supplementary four-lobed lamina, the four lobes being in two different planes, and diverging from the midrib, so that the section would resemble [Symbol: Sideways X], the point of intersection of the x representing the position of the midrib. This four-winged lamina is thus very similar to the four-winged filaments described and figured at p. 289, and to the leaf-like anther of Jatropha described by M. Mueller, p. 255.

Cornute leaves (Folia cornuta).—The condition to which this term applies is that in which the midrib, after running for a certain distance, generally nearly to the point of the leaf, suddenly projects, often in a plane different from that of the leaf, and thus forms a small spine-like out-growth. Should this happen to be terminated by a second laminar portion, an interrupted leaf would be formed. In Scolopendrium vulgare and other ferns this condition has been noticed, as also in some of the varieties of Codiaeum variegatum already referred to.

Flattening.—There are some plants whose stem or branches, instead of assuming the ordinary cylindrical form, are compressed or flattened; such are some species of Epiphyllum, Coccoloba, Bauhinia, &c. The same thing occurs in the leaf-like branches of Ruscus, the flower-stalks of Xylophylla, Phyllanthus, Pterisanthes. Martins proposes to apply the word 'cladodium' to such expansions, just as the term phyllodium is applied to the similar dilatation of the leaf-stalks. If we exclude instances of fasciation, i.e. where several branches are fused together and flattened, we must admit that this flattening does not occur very often as a teratological appearance.

Mr. Rennie figures and describes a root of a tree which had become greatly flattened in its passage between the stones at the bottom of a stream, and had become, as it were, moulded to the stones with which it came into contact.[364]

The spadix of Arum, as also of the cocoa-nut palm, has been observed flattened out, apparently without increase in the number of organs.

When the blade of the leaf is suppressed it often happens that the stalk of the leaf is flattened, as it were, by compensation, and the petiole has then much the appearance of a flat ribbon (phyllode). This happens constantly in certain species of Acacia, Oxalis, &c., and has been attributed, but doubtless erroneously, to the fusion of the leaflets in an early state of development and in the position of rest.[365]

In some water plants, as Sagittaria, Alisma, Potamogeton, &c., the leaf-stalks are apt to get flattened out into ribbon-like bodies; and Olivier has figured and described a Cyclamen, called by him C. linearifolium, in which, owing to the suppression of the lamina, the petiole had become dilated into a ribbon-like expansion—deformation rubanee of Moquin.

FOOTNOTES:

[350] Moore, 'Nature Printed Ferns,' 8vo edition, vol. ii, p. 154, et p. 173.

[351] 'Flora (B. Z.),' 1821, vol. iv, p. 717, c. tab.

[352] Chavannes, 'Mon. Antirrh.'

[353] 'Bull. Soc. Bot. France,' t. vii, 1860, p. 877.

[354] Ibid., t. iv, 1857, p. 759.

[355] Jaeger, "De monstrosa folii Phoenicis dactyliferae conformatione a Goetheo olim observata," 'Act. Acad. Leop. Car. Nat. Cur.,' vol. xvii, suppl., p. 293, c. tab. color. iv.

[356] See Goethe, 'Ueber die spiral Tendenz.'

[357] See Darwin "On Climbing Plants," 'Journ. Linn. Soc. Botany,' vol. ix, p. 5.

[358] 'Ephem. Nat. Cur.,' dec. 2, ann. 1, 1683, p. 68, fig. 14.

[359] 'Ann. des Scienc. Nat.,' third series, vol. i, 1844, p. 292.

[360] 'Flora' Feb. 4, 1858, p. 69, tab. ii, f. 3, and also 'Flora,' 1860, p. 737, tab. vii, f. 9.

[361] 'Bull. Acad, Belg.,' t. xvii, p. 196, "Lobelia," p. 53, c. tab.

[362] Moore, 'Nature-printed Ferns,' 8vo edition, vol. ii, p. 183.

[363] 'Bull. Soc. Bot. Fr.,' 1860, vol. vii, p. 461. See also Naudin, 'Ann. Sc. Nat.,' 4 ser., t. iv, p. 5. Clos, 'Bull. Soc. Bot. Fr.,' t. iii, p. 546.

[364] London's 'Magazine Nat. Hist.,' vol. ii, p. 463.

[365] C. Morren, 'Bull. Acad. Belg.,' 1852, t. xix, part iii, p. 444.



CHAPTER II.

POLYMORPHY.

Usually the several organs of the same individual plant do not differ to any great extent one from another. One adult leaf has nearly the same appearance and dimensions as another; one flower resembles very closely another flower of the same age and so on. Nevertheless it occasionally happens that there is a very considerable difference in form in the same organs, not only at different times, but it may also be at the same time. Descriptive botanists recognise this occurrence in the case of leaves, and apply the epithet heterophyllous to plants possessed of these variable foliar characters. In the case of the flower, where similar diversity of form occasionally exists, the term dimorphism is used.

As these phenomena appear constantly in particular plants, they are hardly to be looked on, under such circumstances, as abnormal, but where they occur in plants not usually polymorphic, they may be considered as coming within the scope of teratology.

Heterophylly.—As a general rule, the leaves or leaf-organs in each portion of a plant, from the rhizome or underground axis, where it exists, to the carpellary leaf, have their own special configuration, subject only to slight variations, dependent upon age, conditions of growth, &c. The cotyledons are very uniform in shape in each plant, and are scarcely ever subject to variation. The leaves near the base of the stem, the root-leaves as they are not unfrequently called, sometimes differ in form from the stem-leaves; these again differ from the bracts or leaves in proximity to the flower. The floral envelopes themselves, as well as the bud-scales, all have their own allotted form in particular plants, a form by which they may, in most cases, be readily recognised. Hence, then, in the majority of plants there is naturally very considerable difference in the form of the leaf-organs, according to the place they occupy and the functions they have to fulfil; but, in addition to this, it not unfrequently happens that the leaf-organs in the same portion of the stem are subject to great variation in form. This is the condition to which the term heterophylly properly applies. The variation in form is usually dependent on a greater or less degree of lobing of the margin of the leaf; thus, in the yellow jasmine, almost every intermediate stage may be traced from an ovate entire leaf to one very deeply and irregularly stalked. Broussonettia papyrifera, and Laurus Sassafras, and the species of Panax, may be mentioned as presenting this condition. Sometimes in the last-named genus, as also in Pteridophyllum, every gradation between simple and compound leaves may be traced. The horse-radish (Cochlearia Armoracia) may also be instanced as a common illustration of polymorphism in the leaves. In ferns it is likewise of frequent occurrence, markedly so in Scolopendrium D'Urvillei, in which plant every gradation from a simple oblong frond to an exceedingly divided one may be found springing from the same rhizome at the same time.