A similar protean state, but little less remarkable, occurs in many of our British ferns, notably in Scolopendrium vulgare, of which Mr. Moore enumerates no fewer than 155 varieties,[366] many of the forms occurring on the same plant at the same time. Cultivators have availed themselves of this tendency to produce multiform foliage, not only for the purposes of decoration or curiosity, as in the many cut-leaved or crisped-leaved varieties, but also for more material uses, as, for instance, the many varieties of cabbages, of lettuces, &c. Most of these variations are mentioned under the head of the particular morphological change of which they are illustrations.

The effect of a change in the conditions of growth in producing diversity in the form of the leaf may be here alluded to. Ficus stipulata, a plant used to cover the walls of plant-stoves in this country, and growing naturally on walls in India, like ivy, produces leaves of very different form, size, and texture, when grown as a standard, from what it does when adhering to a wall. Marcgraavia umbellata furnishes another example of a similar nature, as indeed, to a less extent, does the common ivy.

Allusion has been already made to the occasional persistence of forms in adult life, which are commonly confined to a young state, as in the case of some conifers which present on the same plant, at the same time, two different forms of leaves. Mention has also been made of the presence of adventitious buds on leaves and in other situations. The leaves that spring from these buds are usually of the same form as the other leaves of the plant, but now and then they differ. Of this a remarkable illustration is afforded by a fern, Pteris quadriaurita, in which the fronds emerging from an adventitious bud are very different from the ordinary fronds.



Dimorphism.—This term, applied specially to the varied form which the flowers or some of their constituent elements assume on the same plant, is an analogous phenomenon to what has been above spoken of as heterophylly, and, like it, it cannot, except under special circumstances, be considered as of teratological importance. A few illustrative cases, however, may here be cited.

Sir George Mackenzie describes a variety of the potato[367] (Solanum tuberosum), which produces first double and sterile flowers, and subsequently single fertile ones; the other portions of the plant do not differ much.

Stackhousia juncea, according to Clarke, has mixed with its perfect flowers a number of apetalous blossoms destitute of anthers.[368]

This peculiarity is well exemplified in the tribe Gaudichaudieae of the order Malpighiaceae. A. de Jussieu, in his monograph, speaks of these flowers as being very small, green, destitute of petals, or nearly so, with a single, generally imperfect anther; the carpels also are more or less imperfect, but not sufficiently so to prevent some seeds from being formed. A similar production of imperfect flowers has been noticed in many other orders, e.g. Violaceae, Campanulaceae, &c. In some cases these supplementary blossoms are more fertile and prolific in good seeds than are the normally constructed flowers. M. Durieu de Maisonneuve alludes to a case where flowers of this description are produced below the surface of the ground. The plant in question is Scrophularia arguta, and it appears that towards the end of the summer the lowest branches springing from the stem bend downwards, and penetrate the soil; the branches immediately above the lowest ones also bend downwards, but do not always enter the earth. These branches bear fertile flowers: those which are completely below the soil are completely destitute of petals; those which are on the surface have a four-lobed corolla whose divisions are nearly equal, like those of Veronica.[369]

To Sprengel, and specially to Darwin, physiologists are indebted for the demonstration of the relation of di- and trimorphic flowers to fertilisation. In certain genera of orchids, such as Catasetum, &c., flowers of such different form are produced that botanists, without hesitation, considered them as belonging to different genera, until the fact of their occasional production on the same plant showed that they were not of even specific importance. It was reserved for Mr. Darwin to show experimentally that these very different flowers are really sexual forms of one and the same species, ordinarily occurring on different plants, i.e. dioecious, but occasionally formed on the same spike. The same excellent observer has demonstrated that the di- and trimorphic forms of Primula, of Linum, Lythrum, and other plants—forms differing mainly in the relative length of the stamens and styles, are also connected with striking differences in the number of perfect seeds produced. The most perfect degree of fertility is obtained when the stigma of one form is fertilised by the pollen taken from stamens of a corresponding height. On the other hand, when the union is, as Mr. Darwin states, illegitimate, that is, when the pollen is taken from stamens not corresponding in length to the style, more or less complete sterility ensues in the progeny, sometimes even utter infertility, such as happens when two distinct species are crossed, so that, in point of fact, the offspring of these illegitimate unions correspond almost precisely to hybrids.[370]

Mere variations of form arising from hybridisation or other causes hardly fall within the limits of this work, though it is quite impossible to say where variations end and malformations begin. There are, however, two or three cases cited by Mr. Darwin[371] from Gallesio and Risso to which it is desirable to allude. Gallesio impregnated an orange with pollen from a lemon, and the fruit borne on the mother tree had a raised stripe of peel like that of a lemon both in colour and taste, but the pulp was like that of an orange, and included only imperfect seeds. Risso describes a variety of the common orange which produces "rounded-oval leaves, spotted with yellow, borne on petioles, with heart-shaped wings; when these leaves fall off they are succeeded by longer and narrower leaves, with undulated margins, of a pale green colour, embroidered with yellow, borne on foot-stalks without wings. The fruit whilst young is pear-shaped, yellow, longitudinally striated and sweet; but, as it ripens, it becomes spherical, of a reddish-yellow, and bitter."

Sports or bud variations.—These curious departures from the normal form can only be mentioned incidentally in this place, as they pertain more to variation than to malformation.

The occasional production of shoots bearing leaves, flowers, or fruits of a different character from those found on the normal plant, is a fact of which gardeners have largely availed themselves in the cultivation of new varieties. The productions in question have been attributed to various causes, such as cross-breeding, grafting, budding, dissociation of hybrid characters, or reversion to some ancestral form, all of which explanations may be true in certain cases, but none of them supply the clue to the reason why one particular branch should be so affected, and the rest not; or why the same plant, at the same time, as often happens in Pelargoniums, should produce two, three, or more "sports" of a different character.

These bud variations may be perpetuated by grafts or by cuttings, sometimes even by seed. With reference to cuttings a curious circumstance has been observed, viz., that if taken from the lower part of the stem, near the root, the peculiarity is not transmitted, but the young plant reverts to the characters of the typical form (Carriere). This circumstance, however, is not of universal occurrence.

For further particulars on this interesting subject the reader is referred to Darwin's 'Variation of Animals and Plants,' i, p. 373, where numerous references are given, and wherein certain well-known and highly remarkable instances, such as the Cytisus Adami, the trifacial orange, &c., are discussed.

FOOTNOTES:

[366] 'Nature-printed Ferns,' 8vo edition, vol. ii, p. 197.

[367] 'Gard. Chron.,' 1845. p. 790.

[368] 'A New Arrangement of Phaenog. Plants,' p. 36.

[369] 'Bull. Soc. Bot. France,' 1856, t. iii, p. 569.

[370] The reader will find an abstract of Mr. Darwin's views in his work on the 'Variation of Animals and Plants,' vol. ii, p. 181.

[371] Loc. cit., i, 336.



CHAPTER III.

ALTERATIONS OF COLOUR.[372]

Changes in the colour of the several organs of plants are more often either pathological or the result of variation than of malformation properly so called.

Alterations in colour arise from a diminished or an increased amount of colouring matter, or from an unusual distribution of the solid or fluid matters on which the colour depends. The superposition of cells containing colouring material of different tints produces naturally a very different set of hues from those which are manifested when the colours are not blended. Referring the reader to the ordinary text-books on vegetable physiology and chemistry for details as to the nature and disposition of colouring materials in plants under natural circumstances, it will only be necessary to cite a few instances of deviation from the general colour of plants or their organs.

Albinism.—This change is due to the deficient formation of green colouring matter or chlorophyll, and is more a pathological condition than a deformity.

It seems necessary to draw a distinction between this state and ordinary blanching or etiolation. In the former case chlorophyll seems never to be formed in the affected parts, even if they be exposed to light, while an etiolated organ, when placed under favorable circumstances, speedily assumes a green colour. In Richardia aethiopica one or more leaves become occasionally as white as the spathe is usually.

Virescence.—Engelmann[373] pointed out that, so far as flowers were concerned, there are two ways in which they assume a green colour, either by a simple development of chlorophyll in place of the colouring matter proper to the flower, or by an actual development of leaf-like organs in the room of the petals—frondescence. Morren[374] judiciously proposed to keep these two conditions separate, calling the one virescence, the other frondescence (see p. 241).

Many of the cases recorded as reversions of the parts of the flower to leaves are simply instances of virescence; indeed, it is not in all cases easy to distinguish between the two states. The examination of the arrangement of the veins is often of assistance in determining this point; for instance, if, under ordinary circumstances, the venation of the petal be such as is characteristic of the sheath of the leaf, while in the green-coloured flower of the same species the venation is more like that which belongs to the blade of the leaf, the inference would, of course, be that the green colour was due to frondescence or phyllody.

The persistence or duration of petals is often increased when they are subject to this change; instead of falling off speedily they become persistent when so affected.

Some flowers are more liable to virescence than others. The common honeysuckle, Lonicera Periclymenum, is one of these, and it is noticeable in this plant that the calyx remains unaffected—a circumstance which Morren says shows the distinctness of virescence from frondescence; for, in this instance, we have the most foliaceous portion of the flower remaining unchanged, while the corolla and other organs, usually less leaf-like in their nature, assume a green colour; but this may rather be attributed to the axial nature of the so-called adherent calyx. The stamens in these green-flowered honeysuckles are usually green also, but with abortive anthers, and the pistil also is in a rudimentary condition. Umbelliferae are not unfrequently subject to this change, e.g., Torilis Anthriscus, Daucus Carota, Heracleum Sphondylium, Carum carui, &c. Primulaceae, again, are frequently subject to virescence. Among Compositae the following species are recorded as having had green flowers—Cirsium tricephalodes, Senecio vulgaris, Calendula officinalis, Pyrethrum Parthenium, Carduus crispus, Hypochaeris radicata, Hieracium prealtum, Cirsium arvense, Coreopsis Drummondi.[375] In Ranunculaceae virescence has been observed in Delphinium elatum, crassicaule and Ajacis, Anemone hortensis and nemorosa, Aquilegia vulgaris, Ranunculus Philonotis.

Many of these cases, and others that might be cited, are probably instances of frondescence or phyllody (see p. 241).

Chromatism.—This term is here intended to apply specially to those cases in which any organ of a plant assumes a colour approximating to that of the petals, or in which the normal green is replaced by tints of some other colour. To a certain extent the change in question is the same as that spoken of under the head of petalody (see p. 283), but there are cases in which, while the ordinary situation and form are those of leaves, the coloration is that of the petals. Such was the case in the Gesnera mentioned by Morren (see p. 88), and in which a leaf occupied the position of an inflorescence, and became brightly coloured. In tulips the presence of a highly coloured leaf on the flower-stalk, below the flower, is not uncommon. So also the bracts or leaves below the perianth in Anemone coronaria and hortensis not unfrequently assume the coloration usually confined to the parts of the perianth. A similar illustration has presented itself, as this sheet is passing through the press, in which two of the leaflets of the compound leaf of a rose were brightly coloured like the petals, the others being of their ordinary green colour.

The occurrence of coloured bracts, as in Poinsettia, Bougainvillea, &c., is very common under natural conditions, and need not here be further alluded to.

Increased intensity of colour often accompanies teratological changes; an instance has just been alluded to in the Gesnera; the feather hyacinth, Muscari comosum, furnishes another illustration, the adventitious pedicels being brightly coloured.

In fasciated stems, also, of herbaceous plants, it not unfrequently happens that the upper portions of the stem are brightly coloured.

The occurrence of flowers or fruits of different colours on the same plant, or even in the same cluster, is a phenomenon which does not come within the scope of the present book; the reader may, however, be referred to the excellent summary on this subject published by Mr. Darwin in his work on the 'Variation of Animals and Plants under Domestication.'

FOOTNOTES:

[372] These deviations are treated of under the head of alterations of form, because they are not, in a teratological point of view, of sufficient importance to demand a specific heading, while they appeal to the sight in the same way as the deviations from the customary forms of organs.

[373] 'De Antholys,' p. 32, Sec. 38.

[374] 'Bull. Acad. Belg.,' xvii, part 2, p. 131, c. tab.

[375] See Cramer, 'Bildungsabweich,' pp. 17, 55, 82, 65. See also Lucas, 'Verhandl. des Bot. Vereins. Brandenb.,' heft 1, 2, Anchusa. Christ, 'Flora,' 1867. pp. 376, tab. 5, 6, Stachys.



BOOK III.

DEVIATIONS FROM THE ORDINARY NUMBER OF ORGANS.

To a certain extent the number of the organs of a plant is of even greater consequence for purposes of classification than either their form or their arrangement; for instance, the number of cotyledons in the embryo is made the chief basis of separation between the two great groups of flowering plants, the monocotyledons and the dicotyledons. In the one group, moreover, the parts of the flower are arranged in groups or whorls of five; in the other the arrangement is ternary. In mosses the teeth of the peristome are arranged in fours, or in some multiple of that number. So far as the larger groups are concerned, and also in cases where the actual number of parts is small, the numerical relations above described are very constant; on the other hand, in the minor subdivisions, and especially where the absolute number of parts is large, considerable variation may occur, so that descriptive botanists frequently make use of the term indefinite, and apply it to cases where the number of parts is large and variable, or, at any rate, not easy to be estimated.

Considered teratologically, the changes, as regards the number of organs, are readily grouped into those consequent on a decreased and into those resulting from an increased development. The alteration may be absolute or relative. There may be an actual deficiency in the number of parts or an increase in their number, but in either case the change may be simply a restoration of the primitive number, a species of peloria, in fact. An increased number of parts, moreover, may depend not so much on the formation of additional parts as on the subdivision of one.

It seems also desirable to treat separately those cases in which there is an increased number of buds either leaf-buds or flower-buds, as the case may be, as happens in what is termed prolification. This formation of buds occurring, as it does, often in unwonted situations is treated of under the head of alterations of arrangement, the mere increase in number being considered of subordinate importance as contrasted with the altered disposition (see p. 100).



PART I.

INCREASED NUMBER OF ORGANS.

An augmentation in the number of parts may arise from several causes, and may sometimes be more apparent than real. True multiplication exists simply as a result of over-development; the affected organs are repeated sometimes over and over again each in their proper relative position, and without any transmutation of form.

Metamorphy, on the other hand, often gives rise to the impression that parts are increased in number, when it may be that the stamens and pistils, one or both, are not so much increased in number as altered in appearance. The double anemones and ranunculus of gardens, amongst many other analogous illustrations, may be mentioned. In these flowers, owing to the petalody of the stamens and pistils, one or both, an impression of exaggerated number is produced, which is by no means necessarily a true one. Fission or lateral subdivision also gives rise to an apparent increase in number; thus, some so-called double flowers, the elements of which appeared to be increased in numbers, owe the appearance merely to the laciniation or subdivision of their petals.

The French botanists, following Dunal and Moquin, attribute an increase in the number of whorls in the corolla, and other parts of the flower, to a process which they call chorisis, and they consider the augmentation to be due to the splitting of one petal, for instance, into several;—somewhat in the same manner as one may separate successive layers of talc one from the other.

English botanists, on the other hand, have been slow to admit any such process, because, in most instances, no alteration in the law of alternation takes place in these double flowers, and in those few cases where the law is apparently infringed, the deviation is explained by the probable suppression of parts, which were they present would restore the natural arrangement of the flower; and, that this is no imaginary or purely theoretical explanation, is shown by some of the Primulaceae, wherein a second row of stamens is occasionally present in the adult condition, and renders the floral symmetry perfect.

The double daffodil, where there are from forty to fifty petaloid organs instead of fifteen, and wherein each piece exhibits a more or less perfect coronal lobe at the junction of the claw and the limb, has been cited as an objection to chorisis, though it is difficult to see on what grounds.

In Delphinium, as shown by Braun,[376] the stamens and carpels are members of a continuous spiral series, and in the double balsam an extra corolline whorl is produced, without the suppression of the stamens, in the following manner: the ordinary stamens are replaced by petals, the carpels by stamens, while an additional whorl of carpels is produced at the summit of the axis. In this instance, therefore, the doubling is distinctly referrible to an absolute increase in the number of whorls, and not to chorisis.[377]

On the other hand, it must be admitted that there are many cases which are not to be explained in any other way than that suggested by the French botanists before alluded to. Probably, the main difficulty in the way of accepting the doctrine of chorisis is the unfortunate selection of the word used to designate the process; this naturally suggests a splitting of an organ already perfectly formed into two or more portions, either in the same plane as the original organs, "parallel chorisis;" or at right angles to it "collateral chorisis." Indeed, before so much attention had been paid to the way in which the floral organs are developed, it was thought that an actual splitting and dilamination did really take place; Dunal and Moquin both assert as much. The truth would rather seem to be that, in the so-called parallel chorisis at least, the process is one of hypertrophy and over-development rather than of splitting. The adventitious petal or scale is an excrescence or an outgrowth from the primary organ, and formed subsequently to it.

In the case of "compound stamens" the original stamens are first developed each from its own cellular "mamelon," or growing point; and, after a time, other secondary growing points emerge from the primary one, and in this way the stamens are increased in number, without reference, necessarily, to the so-called law of alternation. Outgrowths from leaves, multiplying the laminar surface, are alluded to under the head of hypertrophy, and it is probable that some of the cases of duplication of the flower, or of the formation of adventitious segments outside the ordinary corolla as alluded to in succeeding paragraphs (see Pleiotaxy of the corolla), are due to a similar process.[378]

The formation of parts in unwonted numbers may be merely a reversion to what is supposed to have been the original form, and in this way there may be a restoration of parts that are usually undeveloped or suppressed. There can be little or no doubt that there are in reality six stamens in Orchidaceae, of which one only, under ordinary circumstances, is developed. When the numerical symmetry is restored, as it sometimes is, it is obvious that the augmentation that occurs is of a different character from that arising from a repetition or renewed development of organs. When the increased number arises from multiplication proper, or from repetition, the ordinary laws of alternation are not interfered with, but if from chorisis or "dedoublement," it may happen that the normal arrangement is disturbed.

Without studying the mode of development, it is not in all cases possible to tell under which of the above categories any particular instance should be placed; hence, in the following sections, except where otherwise stated, the cases are grouped according to the appearance presented in the adult condition, rather than to the way in which the changes from the typical condition are brought about. With reference to the foliar organs it is necessary to distinguish those cases in which there is, from any cause, an augmentation in the number of component parts of a whorl, from those in which the increase takes place in the numbers of the whorls themselves.

FOOTNOTES:

[376] Braun, 'Pringsheim Jahrbuch f. Wiss. Bot.,' 1858, 1, p. 307, tab. 22, 23.

[377] Henfrey, 'Jour. Linn. Soc. Bot.,' vol. iii, p. 159.

[378] On the subject of chorisis or dedoublement the reader may profitably consult Moquin-Tandon, 'Ess. sur les Dedoublements,' and the same author in 'Ann. Sc. Nat.,' t. xxvii, p. 236. and 'El. Ter. Veget.,' p. 337. Dunal, 'Consid. Org. Fleur.,' Montpell., 1829, p. 32, note 3. A. de St. Hilaire in 'Ann. Sc. Nat.,' ser. 3, t. iii, p. 355, adnot. Lindley, 'Elements of Botany,' p. 76. Asa Gray. 'Botanical Text Book.'



CHAPTER I.

MULTIPLICATION OF AXILE ORGANS, INFLORESCENCE, ETC.

By Linne an undue number of branches was designated as "plica," from the analogy with the disease of the hair known as plica polonica: "Plicata dicitur planta, cum arbor vel ramus excrescit minimis intertextis ramulis, tanquam plica polonica ex pilis, ceu instar nidi Picae, quod vulgo a genio ortum arbitratur; frequens apud nos in Betula, praesertim Norlandiae, in Carpino Scaniae, nec infrequens in Pinu."[379]

By some of the older authors this condition was called polyclady. In some cases, it would seem to be due to fungi as in the witches' brooms (hexenbesen) of the German forests; in other instances, it is a result of mutilation as after the operation of pollarding.

Moquin-Tandon[380] mentions a case in a grafted ash in the botanic garden of Toulouse, where below the graft there was a large swelling, from which proceeded more than a thousand densely-packed, interlacing branches.

This must have been similar to the condition so commonly met with in the birch, and frequently in the hornbeam and the thorn, and which has prompted so many a schoolboy to climb the tree in quest of the apparent nest. It is probable that some of the large "gnaurs" or "burrs," met with in elms, &c., also in certain varieties of apples, are clusters of adventitious buds, some of which might, and sometimes do, lengthen out into branches.

An increased number of branches also necessarily arises when the flower-buds are replaced by leaf-buds.



Occasionally, a great increase in the number of pedicels, or flower-stalks, may be met with in conjunction with a decreased number of flowers, as in the wig-plant (Rhus Cotinus), or the feather-hyacinth (Bellevalia comosa). In these cases the supernumerary pedicels are often brightly coloured. To this condition Morren gave the name mischomany, from [Greek: mischos], a pedicel, a term which has not generally been adopted.[381]



M. Fournier[382] describes a case in the butcher's broom (Ruscus aculeatus), wherein from the axil of the minute leaf subtending the flower a secondary flattened branch proceeded.

Duchartre[383] cites the case of a hyacinth which, in addition to the usual scape, had a second smaller one by its side terminated by a solitary flower; indeed, such an occurrence is not uncommon.

Some tulips occasionally present three or four, or more, flowers on one inflorescence, but whether from a branching of the primary scape, or from the premature development of some of the axillary bulbils into flowering stems which become adherent to the primary flower-stalk, cannot, in all cases, be determined. Certainly, in some cases examined by me the latter was the case.[384]

Under this head, too, may be included those cases wherein an ordinarily spicate inflorescence becomes paniculate owing to the branching of the axis and the formation of an unwonted number of secondary buds. Instances of this kind may be met with in willows, hazels, alders, and other amentaceous plants. In the case of the hazel the unusual development of male catkins sometimes coincides with an alteration in their position, instead of being placed near the axil of a leaf; they become terminal. Jaeger figures and describes a bunch of Pinus sylvestris bearing in one case seventy minute cones, and in another fifty-nine. These cones preserved the same spiral arrangement among themselves which is proper to the leaves. These latter, indeed, replaced the strobili above.[385]



M. Reichardt describes an analogous case in the same species, and attributes the inordinate number of cones to a fungus (Peridermium pini). In this case there were no less than 227 cones, but each one half the size of the ordinary cones.[386]

Of a similar character is the many-headed pineapple. Among grasses such a branching of the inflorescence is exceedingly common,—which is the more readily understood as the normal inflorescence is in so many cases paniculate. Cultivators have, in some instances, availed themselves of this peculiarity, as in the Egyptian wheat or corn of abundance (Triticum compositum), certain varieties of Maize, etc. Similar exuberant growths occur in Orchidaceae, in Cyperaceae, e.g. Carex, in Restiaceae, and indeed they may be found in any plant with a similar form of inflorescence. In all these cases the branching begins at the lower part of the spike, and extends from below upwards in an indefinite manner, even although the primary inflorescence be definite.

Among the Equisetaceae a similar plurality of spikes occurs often as a result of mutilation.[387] The deviation in question might in some instances be turned to good account, as in the Triticum before mentioned or as in the broccoli shown at fig. 182, though it must be added that the apparent advantages are often counterpoised by some undesirable qualities or by some circumstance which prevents us availing ourselves of the new condition.

Multiplication of Bulbs.—This occurrence has been briefly alluded to previously (see p. 84). The most curious cases are those in which one bulb is placed on the top of another as happened in some bulbs of Leucoium aestivum described by M. Gay.[388] Irmisch described a similar phenomenon in L. vernum; and Mr. Moggridge has communicated drawings of a similar formation in the same species grown in the neighbourhood of Mentone.

From the instances cited it is clear that branching of the inflorescence occurs most frequently in those plants naturally characterised by a dense compact mode of growth, whether that be definite or indefinite, as in spikes, umbels, capitula, &c.; so that compound spikes, umbels, &c., are formed in the place of simple ones (see also prolification of the inflorescence, p. 102).



Increased number of florets in the individual spikelets of grasses is also met with under some circumstances. I have seen this in Hordeum and Lolium, and an instance is figured in Avena by Dr. Wiegmann.[389] M. Duval Jouve[390] records a similar occurrence in Catabrosa aquatica, the spikelets of which contained from two to seven flowers.[391]

FOOTNOTES:

[379] 'Phil Bot.,' Sec. 274.

[380] 'El. Ter. Veget.,' p. 392.

[381] 'Bull. Acad. Belg.,' xvii, part ii, p. 38.

[382] 'Bull. Soc. Bot. Fr.,' vol. iv, 1857. p. 760.

[383] Ibid., vol. viii, 1861, p. 159.

[384] See 'Gard. Chron.,' July, 1866, p. 656, and Clusius, 'Plant. Rar.,' lib. 2, p. 143, Tulipa serotina [Greek: polyklades], minor, &c. Hort. Eysttett. Plant. Vern.,' fol. 12.

[385] 'Jaeger de Pini sylvestris monstrositate,' Stuttgardt, 1828.

[386] Cited in 'Bull. Soc. Bot. Fr.,' xiv, p. 265.

[387] Duval Jouve, 'Hist. Nat. Equiset. Fr.,' tab. 8, also Milde, 'Nov. Act. Acad. Nat. Cur.,' t. xxvi, part 2. For branched inflorescence of orchids, see 'Reichenbach Proc. Lond. Bot. Congress,' 1866, p. 121.

[388] 'Bull. Soc. Bot. Fr.,' vi, 266, vii, 457. Irmisch, 'Knollen und Zwiebelgew.,' tab. 7, figs. 10, 11.

[389] 'Flora,' 1831, p. 5, tab. i; see also Hanstein, 'Flora,' 1857, p. 513. Schlechtendal, 'Bot. Zeit.,' xviii, p. 381.

[390] 'Bull. Soc. Bot. Fr.,' ix, p. 8.

[391] It will be seen, from what has been just said, that in some of the cases where the axile organs, branches, &c., appear to be multiplied, the increased number is due to subdivision rather than to renewed formation (see Fission). Of this last description is an instance which came under the writer's notice after the section relating to that subject was in print, and which may therefore here be alluded to. The instance is that of the subdivision of the leaf-like organs of Sciadopitys verticillata. In one instance the pseudo leaf divided, and from the division proceeded a little axis, bearing at its summit a verticil of pseudo leaves. This division and formation of new axes and verticils affords ample confirmation of the opinion thrown out by Professor Alexander Dickson, that the apparent leaves of this plant were really branches: see 'Revue Horticole,' 1867, and 'Report. Bot. Congress,' London, 1866, p. 124.



CHAPTER II.

MULTIPLICATION OF FOLIAR ORGANS.

The cases referrible to this head may be ranged under two sections according as the increase is due to plurality of ordinarily single organs, or to an increase in the number of verticils or whorls.

When, in place of a single leaf organ two or more are really or in appearance present the occurrence may be due to one of several causes; among them may be mentioned an actual formation of parts in unwonted number, hypertrophy or enation, chorisis or fission, disjunction, adhesion of one leaf to another or to the stem, as in some of the leaves called "geminate," wherein the two leaves, though apparently in juxtaposition, yet originate from different parts of the stem, but by coalescence or lack of separation produce the impression as if they sprang from the same node. In the adult state it is not always possible to ascertain with certainty to which of these causes the increase in the number of leaves is due, though a clue to the real state of things may be gained from attention to the distribution of the veins, to the arrangement or phyllotaxy of the leaves, the size and position of the supernumerary organs, &c.

The term "phyllomania," as ordinarily used, is applied to an unwonted development of leafy tissue, as in some begonias where the scales or ramenta are replaced by small leaflets, or as in some cabbage leaves, from the surface of which project, at right angles to the primary plane, other secondary leafy plates; but these are, strictly speaking, cases of hypertrophy (see Hypertrophy).

Those instances in which the actual number of leaves is increased, so that in place of one there are more leaflets, may be included under the term "pleiophylly," which may serve to designate both the appearance of two or more leaves in the place usually occupied by a single one, and also those normally compound leaves in which the number of leaflets is greater than usual.

The increased number of leaves in a whorl may well be designated as "polyphylly," using the word in the same sense as in ordinary descriptive botany, while "pleiotaxy" may be applied to those cases in which the number of whorls is increased.



Pleiophylly.—As above stated, this term is proposed to designate those cases in which there is an absolute increase in the number of leaves starting from one particular point, as well as those in which the number of leaflets in a compound leaf is preternaturally increased. The simplest cases are such as are figured in the adjacent cuts, wherein, in place of a single leaf, two are produced in the elm. In the one case the new leaflet springs from the apex of the petiole and partially fills the space consequent on the obliquity of the base of the leaf. In the other it would seem as if two distinct leaves emerged from the stem in juxtaposition. This is probably due to a lateral chorisis or subdivision of the primitive tubercle or growing point, followed by a like subdivision of the vascular bundle supplying it. There are certain varieties of elm that very generally present this anomaly on their rank, coarse, growing shoots. In these cases the new growths have the same direction as the primary one, but in other cases the supplementary production is exactly reversed in direction. Thus, in the common hazel (Corylus) a second smaller leaf proceeding from the end of the leaf-stalk at the base of the primary one may frequently be seen. M. Germain de Saint Pierre records an instance in a mulberry leaf, from the base of which proceeded a large leafy expansion divided into two tubular, horn-like projections, and in the centre a thread-like process representing the midrib and terminated by a small two-lipped limb.[392] Dr. Ferdinand Mueller speaks of a leaf of Pomaderris elliptica as bearing a secondary leaf on its under surface.[393]



The leaves of Heterocentron macrodon have likewise been observed occasionally to produce leaflets from their upper surface.

To this production of leaves from leaves the late Professor Morren applied the term "autophyllogeny."[394] The Belgian botanist figures a small perfect leaf springing from the nerves of the upper surface of the primary leaf in a species of Miconia. As in the hazel, the direction of the adventitious leaf is inversely that of the primary one, the upper surface of the supernumerary leaflet being turned towards the corresponding surface of the normal leaf. A similar occurrence took place in Gesnera zebrina, but the new growth in this case sprang from the lower face of the leaf. Morren explains the appearances in question by supposing that the supplementary leaf is one of a pair belonging to a bud borne on a slender stalk. This stalk and one of the bud-leaves are supposed to be inseparably united with the primary leaf. But there is no reason at all for supposing the existence of adhesion in these cases; no trace of any such union is to be seen. A much more natural explanation is that, from some cause or another, development at the apex of the petiole or on the surface of the nerves, instead of taking place in one plane only, as usual, takes place in more than one, thus showing the close relationship, if not the intrinsic identity, between the leaf-stalk and its continuation, the midrib, with the branch and its subdivisions. The form of the leaf-stalk and the arrangement of the vascular bundles in a circle in the case of the hazel, before alluded to, bear out this notion. Such cases are significant in reference to the notion propounded by M. Casimir de Candolle, that the leaf is the equivalent of a branch in which the upper portion of the vascular circle is abortive.[395]

Compound leaves, as has been stated, occasionally produce an extra number of leaflets; one of the most familiar illustrations of this is in the case of the four-leaved shamrock (Trifolium repens), which was gathered at night-time during the full moon by sorceresses, who mixed it with vervain and other ingredients, while young girls in search of a token of perfect happiness made quest of the plant by day. Linne, who in this matter, at any rate, had less than his usual feeling for romance, says of the four-leaved trefoil that it differs no more from the ordinary trefoil than a man with six fingers differs from one provided with the ordinary number. It should be stated that five and six adventitious leaflets are found almost as frequently as four.

Walpers describes a case where the leaf of T. repens bore seven leaflets. Schlechtendal alludes to a similar increase in number in Cytisus Laburnum, and many other instances might be cited.

For figures or descriptions of four-leaved shamrocks the reader is referred to Lobel, 'Stirp. Advers.,' Nov., p. 382. Tabernaemontanus 'Krauterbuch,' S. 222. Schlechtendal, 'Bot. Zeit.,' ix, p. 583, xiv, p. 71. Maugin, 'Bull. Soc Bot. Fr.,' 1866, t. xiii, p. 279. See also Cramer, 'Bildungsabweich,' p. 92. Walpers, 'Linnaea,' 1840, p. 362 (7-leaved). Schlechtendal, 'Bot. Zeit.,' 1844, p. 457, Cytisus. Wigand, 'Flora,' 1856, p. 706.

Frondiferous leaves have much the appearance of branches provided with leaves, and they may be compared with those instances in which an adventitious bud is placed on the surface or edges of the leaves, as in Gesnera, Cardamine, &c. In truth, the two conditions merge one into the other, as in some begonias, where the ramenta often become leaf-like and bear small bulbils in the axil.

When frondiferous leaves die the appendages die also, but when a true bud has been formed on a leaf it does not of necessity die with the leaf that bears it, but separates from it and continues to grow independently.

Increased number of stipules, spathes, &c.—Seringe relates the occasional presence of two or three additional stipules upon the leaf-stalks of Salix fragilis, and even makes a variety (Salix pendula, var. multistipulata).

An increase in the number of the spathes has been often noticed in Arads[396]. Prof. Alex. Braun has studied this subject in some detail[397]. In Calla palustris the shoot which continues the growth of the plant proceeds from the axil of the last leaf but one; the very last leaf producing no bud, but if accidentally a shoot is developed in this latter situation it produces flowers at once. No leaves are formed, but, on the contrary, two or three spathes surround the spadix, so that the presence of an increased number of spathes in this plant is associated with the development of a side shoot from the axil of the last leaf, the situation whence, under natural circumstances, no shoot at all issues. The supernumerary spathes are not always on the same level, but may be separated by a considerable interval. They vary very much in size, and sometimes assume the form and appearance of leaves. Similar anomalies occur in other Arads as Arum maculatum, Richardia aethiopica, and Anthurium Scherzerianum, frequently combined with a leaf-like appearance of the spathes and sometimes with a subdivision of the spadix into two or three branches.

Engelmann relates the occurrence of an increased number of glumes in Bromus velutinus associated with suppression of the flowers.

Polyphylly.—As previously explained, this term is here applied to those cases in which the members of any particular whorl are increased in number, the whorls themselves not necessarily being augmented.

The simplest cases of this kind are those in which we meet with an unusual number of leaves in a whorl.

Increased number of leaves in a whorl.—This may arise from actual multiplication, or from lateral chorisis, or fission. The true nature of the case may usually be ascertained by an examination of the distribution of the veins of the leaves, or of the fibrous cords of the stem, by the relative position of the supernumerary organs, &c.

Among plants with normally opposite leaves the following occasionally produce them in whorls of three:—Lonicera brachypoda, L. Xylosteum, Weigela rosea, Cornus mas, Vinca minor, &c.

Paris quadrifolia may frequently be met with five leaves in its whorl, or even six.[398]

Increased number of bracts.—This is not of infrequent occurrence; one of the most curious instances is that recorded by Mr. Edwards[399] in Cerastium glomeratum, where, in place of the usual pair of bracts at the base of the head of flowers, there was a whorl of six or eight, forming an involucre. The flowers in this case were apetalous and imperfect.

Polyphylly of the calyx.—This may occur without any other perceptible change, while at other times the number of the other parts of the flower is proportionately increased. In a flower of a plum six sepals in place of five sometimes exist; a precisely similar occurrence in the flowers of the elder (Sambucus), the Fuchsia, and of OEnanthe crocata, may occasionally be met with. In the latter case, indeed, there are sometimes as many as ten segments to the calyx, and this without the other parts of the flower being correspondingly augmented. Among monocotyledons a similar increase is not uncommon, as in Tulipa, Allium, Iris, Narcissus, &c.

In some plants there seems to exist normally much variation in the number of parts; thus in some species of Lacistema in adjacent flowers the calyx may be found with four, five, or six segments.

Most of these cases of polyphylly affecting the calyx may be explained by lateral chorisis or fission.

Polyphylly of the corolla.—This may happen in connection with similar alterations in the calyx and stamens, or sometimes as an isolated occurrence. In the latter case it may be due to lateral chorisis, to substitution, or to the development of organs usually suppressed; thus, when in aconites we meet with four or five horn-like nectaries (petals) instead of two only, as usual, the supernumerary ones are accounted for by the inordinate development of parts which ordinarily are in an abortive or rudimentary state only. This is borne out by what happens in Balsamineae. In the common garden balsam the fifth petal is occasionally present, while in Hydrocera triflora this petal is always present.

In a flower of a Cyclamen recently examined there were ten petals in one series, the additional five being evidently due to the subdivision of the five primary ones; the natural circular plan of the flower was here replaced by an elliptical one. A similar occurrence takes place in the flowers of maples (Acer), which sometimes show an increased number of parts in their floral whorls and an elliptical outline. Whether the additional organs in this last case are the result of complete lateral chorisis or of multiplication proper I do not know.

Orchids are very subject to an increase in the number of their labella. As illustrations may be cited an instance recorded by Mr. J. T. Moggridge in a flower of Ophrys insectifera, and in which there were two labella without any other visible deviation from the ordinary conformation.[400]

I am indebted to Mr. Hemsley for the communication of a similar specimen in O. apifera, in which there were two divergent lips, each with the same peculiar markings. One of the sepals in this flower was adherent to one of the lateral petals. This augmentation of the labella depends sometimes on the separation, one from the other, of the elements of which the lip is composed, at other times on the development, in the guise of lips, of stamens which are usually suppressed (see p. 380).

The following enumeration will suffice to show the genera in which an increased number of petals or perianth-segments in any given whorl most frequently occurs.

Anemone! Ranunculus! Aconitum! Raphanus. Bunias. Saponaria. Dianthus! Pelargonium! Hibiscus. Fuchsia. Sarothamnus! Lotus! Ulex! Prunus! Trifolium. OEnanthe and Umbellif. pl.! Sambucus! Bryonia. Campanula. Solanum. Veronica. Cyclamen! Primula! Anagallis! Plumbago. Jasminum. Syringa! Tradescantia. Iris. Tigridia. Narcissus. Tulipa. Convallaria! Paris! Hyacinthus! Allium! Ornithogalum. Orchideae, sp. pl.!

For other illustrations see multiplication of whorls, petalody; see also Moquin, loc. cit., p. 350. Engelmann, loc. cit., p. 20, Sec. 18. Cramer, loc. cit., p. 25.

Polyphylly of the androecium.—An increased number of stamens frequently accompanies the corresponding alterations in other whorls, and seems, if anything, to be more frequent among monocotyledonous plants than among dicotyledonous ones; thus, we occasionally find tetramerous flowers in Crocus, Hyacinthus, Tulipa, Iris, Tigridia, &c., and more rarely in Yucca (Y. flexilis[401]).

The increased number of stamens in a single whorl may result from a development of organs usually suppressed, and constitute a form of regular peloria as in Linaria, wherein a fifth stamen is occasionally met with. Among normally didynamous plants such numerical restitution, so to speak, is not unusual; thus, in Veronica four and five stamens occur. Fresenius has seen five stamens in Lamium, Mentha, Chelone;[402] Bentham in Melittis, and other instances are cited under the head of peloria. Chorisis may also serve to account for some of these cases; thus, Eichler[403] figures a flower of Matthiola annua with five long stamens instead of four; one of the long pairs of stamens has here undergone a greater degree of repetition than usual. De Candolle[404] cites and figures a curious form of Capsella Bursa-pastoris sent him by Jacquin, and which was to some extent reproduced by seed. In the flowers of this variety there were no petals, but ten stamens; hence De Candolle inferred that the petals were here replaced by stamens, but Moquin[405] objects, and with justice, to this view, as the ten stamens are all on the same line; he considers the additional stamens to be the result of chorisis. Buchenau[406] mentions the presence of seven stamens in another Crucifer, Ionopsidium acaule. Here the supernumerary organ was placed between two of the long stamens. The effect of chorisis in producing an augmentation of parts is well seen in some plants that have some of their flowers provided with staminodes or abortive stamens, and others with clusters or phalanges of perfect stamens. Thus, in the female flowers of Liquidambar there are five small staminodes without anthers, whereas in the male flower the stamens are numerous and grouped together in phalanges, so that the relation of simple to compound stamens is in this case readily seen, as also in many Malvaceae, Sterculiaceae, Byttneriaceae, Tiliaceae, and Myrtaceae. It is probably the idea of splitting or dilamination involved in the word chorisis that has led many English botanists to hesitate about accepting the notion. Had they looked upon the process as identical with that by which a branched inflorescence replaces an unbranched one, or a compound leaf takes the place of a simple one, the objections would not have been raised with such force. The process consists, in most cases, not so much in actual cleavage of a pre-existing organ as in the development of new-growing points from the old ones.

An illustration given by Moquin from Dunal[407] goes far to support the notion here adopted. The majority of the stamens of laurels (Laurus) have, says M. Dunal, on each side of the base of their filaments a small glandular bifid appendage; these excrescences are liable to be changed into small stamens. The male flowers have a four-leaved calyx, and sometimes eight stamens, each with two glands, four in one row, opposite to the sepals, four in a second series alternating with the first. More generally two of the stamens are destitute of glands, but have in their place a perfectly developed stamen, so that in these latter flowers there are twelve stamens.

M. Clos[408] mentions a flower of rue (Ruta) wherein there were two stamens joined together below and placed in front of a petal, as in Peganum.

Buchenau[409] mentions a flower of Lotus uliginosus in which there were eleven stamens, namely, two free and nine monadelphous; and Hildebrand describes an analogous increase in a flower of Sarothamnus scoparius in which, in conjunction with a seven-toothed calyx, there were two carinas and fourteen stamens. It would seem probable in this case that there was a coalescence of two flowers at an early date and consequent suppression of some of the parts of the flower. Whether this was the case or not in this particular illustration, it is nevertheless certain that many of the recorded instances of increased number in the organs of a flower are really the results of a fusion of two or more flowers, though frequently in the adult state but few traces of the coalescence are to be seen.

Polyphylly of the gynoecium.—Moquin[410] remarks that, as the pistils are, generally speaking, more or less subject to pressure, owing to their central position, and it may be added owing to their later development, than the other parts of the flower, they are more subject to suppression than to multiplication; nevertheless, augmentation in the number of carpels does occasionally take place, especially when the other parts of the flower are also augmented in number. Sometimes this increase in the number of carpels is due to pure multiplication, without any other change. At other times the increase is due to a substitution of stamens or other organs for carpels (see Substitutions). In other cases the augmentation seems to be due to the development of parts usually suppressed; for instance, in Antirrhinum, where there are usually only two carpels present, but where, under peculiar circumstances, five may be found—thus rendering the symmetry complete.[411] In Papilionaceae, wherein usually only one carpel is developed, we occasionally find two, or even more, as in Wistaria, Gleditschia, Trifolium, &c. In Prunus and Amygdalus from two to five carpels are occasionally to be found,[412] in Mimosa five, in Umbelliferae three to five; in some composites, e.g. Spilanthes, five carpels have also been noticed; in Cruciferae three and four, in grasses three.[413] The double cocoa-nut affords an illustration of the development of two carpels out of three, one only generally arriving at perfection. Triple nuts (Corylus) also owe their peculiarity to the equal development of all three carpels which exist in the original flower, but of which, under ordinary circumstances, two become abortive. It is necessary, however, to distinguish these cases from those in which two embryos are developed in one seed.

The following list may serve to show in what genera this change has been most frequently noticed, and it may be said in general terms that Cruciferae, Umbelliferae, and Liliaceae, are the orders most frequently affected. Cases of peloria are not included in the subjoined list.

Nigella. Aquilegia. Paeonia! Delphinium! Iberis. Diplotaxis. Lunaria. Ricotiana. Octadenia. Draba! Lepidium. *Cheiranthus! Dianthus. Brassica! Parnassia. *Acer! Ptelea. Citrus! Philadelphus. Prunus! Amygdalus! Crataegus! Fuchsia! Trapa! Cassia. Cercis. Medicago. *Phaseolus! Wistaria. Gleditschia. Affonsea. Trifolium! Archidendron. Mimosa. Robinia. Diphaca. Coesalpinia. Vicia. Anthyllis. Cucurbita. Passiflora! Sambucus! *OEnanthe! Daucus! Angelica! Heracleum! Silaus. Carum. Thysselinum. Campanula! Spilanthes. Chrysanthemum. Anagallis. Primula! Fraxinus! Lycium. Cobaea. Datura! Solanum! Sesamum. Sideritis. Coleus. Veronica! *Digitalis! Antirrhinum! Linaria. Gloxinia! Symphytum. Anchusa. Polygonum. Euphorbia. Cneorum. Mercurialis! Chenopodium. Suaeda. Beta. Corylus! Lambertia. Cocos! Tigridia. Tulipa! Iris! Narcissus! Allium! Ornithogalum. Gagea! Tradescantia! Schoenodon. Bambuseae.

A few additional references may here be given to papers where an increased number of carpels is described:—Engelmann, 'De Antholys,' Sec. 17, p. 19. Bernhardi, 'Flora,' 1838, p. 129. Schkuhr., 'Bot. Handb.,' t. 179. Godron, 'Ann. Sc. Nat.,' ser. 5, vol. ii, p. 280, tab. xviii, pluricarpellary Crucifers. Weber, 'Verhandl. Nat. Hist. Vereins. Rhein. Pruss.,' &c., 1860, Cerasus, &c., &c. Baillon, 'Adansonia,' iv, p. 71, Trifolium. Schlechtendal, 'Bot. Zeit.,' xv, p. 67, Datura, three-celled fruit; 'Bot. Zeit.,' xiii, p. 823, Phaseolus, double pistil—a common case. Cramer, 'Bildungsabweich,' p. 99, reference to several leguminous plants with polycarpellary pistils. Munro, Gen., 'Linn. Trans.,' vol. xxvi, p. 26, Bambuseae. Alph. de Candolle, 'Neue Denkschrift,' Cheiranthus. Schimper, 'Flora,' 1829, ii, p. 433. Wigand, 'Bot. Untersuch.' Fleischer, 'Missbild. Cultur Pfl.' Cramer, 'Bildungsabweich,' p. 65, Umbelliferae.

Polyphylly of the flower in general.—Although, for the sake of convenience, multiplication has here been treated of as it affects the members of individual whorls of the flower, yet it must be remembered that, in general, the augmentation is not confined to one whorl, but affects several; thus, if the sepals are increased, the petals are likely to be so likewise, and so forth. One of the most curious illustrations of this is that recorded by Mr. Berkeley[414] in a plum, wherein there was an increased number of sepals, a corresponding augmentation in the petals, while the pistil was composed of two and sometimes three carpels distinct from the calyx and from each other. In the flowers there did not appear to be any definite relation in the position of the parts either with reference one to another or to the axis.



In Primulaceae this general augmentation has been frequently noticed.[415]

Among Orchideae the instance related by Dr. Seubert is worth alluding to here. This botanist observed and figured a flower of Orchis palustris with tetramerous arrangement of parts, that is to say there were four outer segments to the perianth, four petals, of which two were lip-like, four stamens, three of which were rudimentary, and an ovary with four parietal placentae.[416]

The following list will serve to show in what plants this general augmentation of parts has been observed most frequently:

Ranunculus. Clematis! Delphinium. Brassica! Ruta. Acer! Prunus! Rosa! Rubus. Philadelphus! Chrysosplenium. Umbelliferae, sp. pl.! *Fuchsia! OEnothera. Adoxa. Bryonia. Cucumis! Campanula! Sambucus! *Primula! Anagallis! Lycium. Solanum. Symphytum. Syringa! Linaria. Chenopodium. *Paris! Convallaria! Allium. *Lilium! *Tulipa! Ornithogalum. *Gagea! Tradescantia! Orchideae, sp. pl.!

Increased number of ovules or seeds.—This appears not to be of very frequent occurrence, at least in those plants where the number of these organs is normally small; where, as in Primula, the ovules and seeds are produced in large quantities, it is not practicable to ascertain whether the number be augmented or not in any particular case. Very probably, the attachment or source of origin of the ovules determines, in some measure, their number. Thus, in the case of marginal placentation the number must be limited by the narrow space from which they proceed, whereas in parietal and free central placentation the ovules are generally numerous. In the latter case, however, it will be remembered that solitary ovules are not rare. An increased number of ovules is generally remarked in conjunction with some other change, such as a foliaceous condition of the carpel, in which the margins are disunited. In such cases the ovules may occupy the margin or may be placed a short distance within it, as in the case of some open carpels of Ranunculus Ficaria,[417] and in which two ovules were borne in shallow depressions on the upper or inner surface of the open carpel and supplied with vascular cords from the central bundle or midrib. The outer coating of the ovule here contained barred or spiral fusiform vessels derived from the source just indicated.

In the very common cases where the pistil of Trifolium repens becomes foliaceous (see Frondescence), the outer ovules are generally two or more instead of being solitary. So, also, in the Rose with polliniferous ovules (see p. 274). Among Umbelliferae affected with frondescence of the pistil a similar increase in the number of ovules takes place. It will be borne in mind that in most, if not all, these cases the structure of the ovule is itself imperfect.[418]

What are called in popular parlance double almonds or double nuts (Corylus) are cases where two seeds are developed in place of one.

In the 'Revue Horticole,' 1867, p. 382, mention is made of a bush which produces these double nuts each year—in fact, it never produces any single-seeded fruit. The plant was a chance seedling, perhaps itself the offspring of a double-seeded parent. It would be interesting to observe if the character be retained by the original plant, and whether it can be perpetuated by seed or by grafting.

It is necessary to distinguish in the case of the nut between additional seeds or ovules, as just described, and the double, triple, or fourfold nuts that are occasionally met with, and which are the result either of actual multiplication of the carpels or of the continued development of some of the carpels which, under ordinary circumstances cease to grow (see ante, p. 364). In the case of a ripe nut with two seeds it might be impossible to tell whether the adventitious seed were the product of multiplication, or whether it belonged, in the first instance, to the same carpel as that producing the fellow-seed, or to a different and now obliterated ovary. In all probability, however, the second seed would be accounted for by the development of two seeds in one carpellary cavity.

There is still another condition occasionally met with in the almond, and which must be discriminated from the more common multiplication of the seed, and which is the multiplication of the embryos within the seed, and which furnishes the subject of the succeeding paragraph.

Increased number of embryos.—A ripe seed usually contains but a single embryo, although in the ovular state preparation is commonly made for more; and, indeed, in certain natural orders plurality of embryos in the same seed does occur, as in Cycadeae and Coniferae. In the seeds of the orange (Citrus), in those of some Euphorbiaceae, &c., there are frequently two or more additional embryos. A similar occurrence has been recorded in the mango, for a specimen of which I am indebted to the Rev. Mr. Parish, of Moulmein.[419]

Plurality of embryos has also been observed in—

Raphanus sativus. *Citrus Aurantium! Diosma, sp. Hypericum perforatum. Triphasia aurantiaca. *AEsculus Hippocastanum! Euonymus latifolius. *Mangifera indica! Eugenia Jambos. Amygdalus vulgaris! Vicia, sp. Cassia, sp. *Viscum album! Daucus Carota. Ardisia serrulata! Cynanchum nigrum. fuscatum. Euphorbia rosea. Coelebogyne ilicifolia. Allium fragrans. Funckia, sp. Carex maritima. Zea Mays.

See Schauer's translation of Moquin-Tandon, 'El. Terat. Veget.,' p. 245, adnot., and 'Al. Braun Polyembryonie.'

Increased number of the cotyledons.—Although the presence of one or of two cotyledons in the embryo is generally accepted as a valuable means of separating flowering plants into two primary groups, yet, like all other means of discrimination, it occasionally fails, and, indeed, almost always requires to be taken in conjunction with some other character. There are cases among flowering plants where the embryo is homogeneous in its structure, there are others in which the number of the cotyledons is more than two. Thus, in some seeds of Cola acuminata the cotyledons vary in number from two to five. I have not been able to ascertain precisely whether this multiplication of the cotyledons is characteristic of all the seeds of particular trees, or whether some only are thus affected. Some fruits that I examined bore out the latter view, as in the same pod were seeds with two, three, and four cotyledons respectively.

I have also seen three cotyledons present in embryo-plants of Correa, Crataegus Oxyacantha, Dianthus sinensis, Daucus Carota, Cerasus Lauro-cerasus. De Candolle alludes to a case of the kind in the bean, and figures a species of Solanum with three cotyledons.[420] Jaeger alludes to a similar instance in Apium Petroselinum;[421] Ehrenberg to one in the marigold (Calendula);[422] Reinsch to an analogous appearance in the beech (Fagus), associated with a union of the margins of two out of the three cotyledons, and of those of two out of the three leaves next adjacent.[423] This fusion seems frequently to accompany increase in the number of cotyledons. It was so in the Correa, and in the Crataegus previously mentioned. Some of these cases may be accounted for by chorisis or by a cleavage of the original cotyledons, as happens, according to Duchartre,[424] in some Coniferae, which he considers to be improperly termed polycotyledonous. Whether this holds good in the Loranths, where (Nuytsia, Psittacanthus) an appearance of polycotyledony exists, is not stated. In the case of the rue (Ruta) figured by M. A. de Jussieu[425] this splitting of one cotyledon into two is sufficiently evident, as is also the case in the sycamore (Acer pseudo-platanus), seedlings of which may often be met with divided cotyledons.

In other instances a fusion of two embryo plants may give rise to a similar appearance, as in the Euphorbia and Sinapis found by M. Alph. de Candolle (see ante, p. 56).

Pleiotaxy or multiplication of whorls.—In the preceding section notice has been taken of the increased number of parts in a single whorl, but an augmentation of the number of distinct whorls is still more frequently met with. Many of the so-called double flowers owe their peculiarity to this condition. The distinction between the two modes in which the parts of the flower are increased in number has been pointed out by Engelmann, Moquin, and others, and the two seem to require distinctive epithets; hence the application of the terms polyphylly and pleiotaxy, as here proposed.

Pleiotaxy in the bracts.—An increase in the number of bracts has been met with very constantly in a species of Maesa, and in a peculiar variety of carnation, called the wheat-ear carnation.[426] In some of these cases the increase in the number of bracts is attended by a corresponding suppression in the other parts of the flower. Such a condition has been frequently met with in Gentiana Amarella, where the bracts are increased in number, coloured purple, and destitute of any true floral organs. A similar condition exists in some varieties of Plantago major (var. paniculata), as has been previously stated, p. 109.



It has been noticed also in the common pea, Pisum sativum, and M. Lortet[427] records a case of the kind in Erica multiflora, the flowers of which, under ordinary circumstances, are arranged in clusters, but in this case the pedicels were more closely crowded than usual, and were covered for their whole length with small rose-coloured bracts arranged in irregular whorls, the upper ones sometimes enclosing imperfect flowers. In the 'Gardeners' Chronicle,' 1865, p. 769, is figured a corresponding instance of Delphinium Consolida, in which the bracts were greatly increased in number, petaloid, and, at the same time, the central organs of the flower were wholly wanting.



In flowers of Pelargonium may occasionally be seen a repetition of the whorls of bracts, in conjunction with suppression and diminished size of some of the other portions of the flower (fig. 189).

The common foxglove (Digitalis purpurea) has likewise occasionally been observed subject to a similar malformation.

Cornus mas and C. suecica sometimes show a triple involucre.[428] Irmish[429] records an analogous case in Anemone Hepatica, wherein the involucre was doubled. Similar augmentation occurs in cultivated Anemone. In addition to the plants already mentioned, Engelmann[430] mentions as having produced bracts in unwonted numbers, Lythrum Salicaria, Plantago major, Veronica spicata, Echium vulgare, Melilotus arvensis, and Rubus fruticosus.

It must here be remarked that this great number of the bracts occurs naturally in such plants as Godoya, in which the bracts, or, as some consider them, the segments of the calyx, are very numerous, and arranged in several overlapping segments.

In some of the cultivated double varieties of Nigella the finely divided involucral bracts are repeated over and over again, but on a diminished scale, to the exclusion of all the other parts of the flower.

Pleiotaxy or repetition of the calyx.—The true calyx is very seldom affected in this manner, unless such organs as the epicalyx of mallows, Potentilla, &c., be considered as really parts of the calyx.

In Linaria vulgaris Roeper observed a calyx consisting of a double series, each of five sepals, in conjunction with other changes.[431] It is also common in double columbines, delphiniums, nigellas, &c.

In the 'Revue Horticole,' 1867, p. 71, fig. 9, is described and figured by M. B. Verlot a curious variety of vine grown for years in the Botanic Garden at Grenoble, under the name of the double-flowered vine. The place of the flower is occupied by a large number of successive whorls of sepals disposed in regular order, and without any trace of the other portions of the flower. It is, in fact, more like a leaf-bud than a flower. The outermost whorls of this flower open at the time when the ordinary flowers of vines do; the second series are gradually produced, and expand about the time when the ovaries of the normal flowers begin to swell; a third series then gradually forms, and so on, until frost puts a stop to the growth. This malformation, it appears, is produced annually in certain varieties of vine, and may be perpetuated by cuttings.

The flower of the St. Valery apple, already alluded to under the head of sepalody, might equally well be placed here. It is not very material whether the second whorl of organs be regarded as a repetition of the calyx or as a row of petals in the guise of sepals.

Engelmann[432] cites the following plants as occasionally presenting a repetition of the calyx, in most cases with a suppression of the other floral whorls:—Stachys lanata, Myosotis palustris, Veronica media, Aquilegia vulgaris, Nigella damascena, Campanula rapunculoides.

Pleiotaxy in the perianth.—Increase in the number of whorls in the perianth is common in lilies, narcissus, hyacinths, &c. It may be also met with occasionally among orchids. The lily of the valley (Convallaria maialis) seems also to be particularly subject to an increase in the number of parts of which its perianth consists, the augmentation being due partly to repetition or pleiotaxy, partly to the substitution of petaloid segments for stamens and pistils.[433]

In this place may also be mentioned the curious deviation from the ordinary structure occasionally met with in Lilium candidum, and known in English gardens as the double white lily. In this case there are no true flowers, but a large number of petal-like segments disposed in an irregular spiral manner at the extremity of the stem, some of the uppermost being occasionally verticillate.[434]



Pleiotaxy of the corolla.—With reference to double flowers, it was remarked by Linne that polypetalous flowers were, as he said, multiplied, while monopetalous flowers were duplicated, or triplicated, as the case may be,[435] a statement that is true in the main, though it requires modification. In the case of polypetalous, or rather dialypetalous flowers, the petals may be very largely increased by multiplication, as in roses, anemones, pinks, &c. In the last-named genus the number is often so much increased that the calyx splits from the tension exercised on it by the increasing mass within. This multiplication may happen without any metamorphy or substitution of petals for stamens, though, in the majority of cases, it is associated with such a change. It is curious to observe in some of these flowers that the total number of parts is not greatly increased; thus, in some of the double-flowered Leguminosae, such as Ulex europaeus and Lotus corniculatus, the petals are repeated once or twice, the stamens are petalodic, but reduced in number, while the carpels are usually entirely wanting. Thus, owing to the diminished number of parts in the inner whorls of the flower, these very double-looking blooms do not contain any greatly increased number of parts.[436]

Flowers that, under ordinary circumstances, are gamopetalous, become, in some instances, multiplied by the formation of additional segments, just as in the case of polypetalous corollas; but in these cases the corollas become polypetalous, their petals do not cohere one with another. Among double flowers of this character may be mentioned Campanula rotundifolia, Gardenia sp., Nerium Oleander, Serissa sp., Arbutus Unedo, &c. The change is associated with petalody of the stamens and pistils.

A more frequent change among the monopetalous orders is the duplication or triplication of the corolla, in consequence of which there appear to be a series of corollas enclosed one within the other, the lobes of which generally alternate with one another, but which sometimes are superposed. This happens occasionally in the primrose (Primula acaulis), and constitutes the variety called by the gardeners "hose in hose."

The same condition occurs frequently in some species of Datura and Campanula.



In Antirrhinum majus double flowers of this character sometimes occur; the outermost corolla is normal, the succeeding ones usually have their petals separate one from the other; the stamens are sometimes present, sometimes absent, and at other times petalodic. Similar occurrences may be met with in labiates and jasmines, and in Erica hyemalis.

Mr. W. B. Hemsley has kindly furnished me with flowers of a similar kind occurring in wild specimens of Epacris impressa,[437] and there are analogous phenomena in the common honeysuckle (Lonicera Periclymenum), in which three corollas and no stamens often occur.

This duplication may either be accounted for on the theory of chorisis above alluded to, or by supposing that the extra corolline whorl is due to a series of confluent petalodic stamens; that the latter is the true explanation, in certain cases at least, is shown by some flowers of Datura fastuosa, in which the second corolla was partially staminal in its appearance, and bore nearly perfect anthers, in addition to the five ordinary stamens, which were unaltered either in form or position. Some partially virescent honeysuckle flowers have a similar structure.

There are other cases of apparent multiplication or duplication, due, probably, rather to the formation of outgrowths from the petals than to actual augmentation of their number. These excrescences occur sometimes on the inner surface of the petals, or of the corolla; at other times on the outer surface, as in some gloxinias, &c. This matter will be more fully treated of under the head of hypertrophy and enation.

Pleiotaxy of the androecium.—An increase in the number of whorls in the stamens is very common, especially in cases where the number of circles of stamens is naturally large. The augmentation of the number of stamens is still more frequent where these organs are arranged, not in verticils, but in one continuous spiral line.

In Cruciferae there is always an indication of two whorls of stamens, and this indication is rendered even more apparent in some varieties accidentally met with. So in Saponaria, in Dianthus, and other Caryophylleae, three and four verticils of stamens have been met with. In Lonicera Periclymenum a second whorl of stamens more or less petalodic sometimes occurs.

Moquin mentions a variety of Rubus fruticosus in which nearly 900 petaloid organs existed in the place of the twenty-five or thirty stamens natural to the plant, the other organs of the flower being in their ordinary condition, with the exception of the pistil, which did not attain its full size. Baillon records the occasional existence of two rows of stamens in Ditaxis lancifolia.

Increased number of stamens in orchids, &c.—Various deviations from the ordinary type of orchid structure have been already alluded to under the head of displacement, fusion, peloria, substitution, &c., but the alterations presented by the androecium in this family are so important in reference to what is considered its natural conformation, that it seems desirable, in this place, to enter upon the teratological appearances presented by the androecium in this order, in somewhat greater detail than usual. The ordinary structure of the flower with its three sepals, two petals, labellum, column; and inferior ovary, is well known. Such a conformation would be wholly anomalous and inexplicable were it not that the real number and arrangement of parts have been revealed by various workers labouring to the same end in different fields. Thus, Robert Brown, Link, Bauer, Darwin, and others, paid special attention to the minute anatomy and mode of distribution of the vessels; Irmisch, Crueger, Payer, and others, to the evolution of the flower; Lindley, St. Hilaire, and Reichenbach, to the comparison of the completed structures in the various genera and species; while the teratological observers have been numerous, as will be seen from the selected references cited at the end of this paragraph and in other places. The result of this manifold study has been a pretty general agreement that the structure of the order (omitting minor details) is as follows:—A six-parted perianth in two rows, the outer three (sepals) generally regular and equal in shape; of the inner three (petals or tepals) two are regular, and one, the labellum very irregular, consisting not only of a petal, but of two abortive stamens incorporated with it. The column is considered to be made up of one perfect and three abortive stamens, in inseparable connection with three styles. By some, however, it is supposed that all the stamens are confluent with the column and none with the lip.



In either case it is admitted that there are six stamens in two rows. The first row consists of one posterior stamen, which is generally perfect, and two abortive stamens incorporated with the labellum. The second row also consists of three stamens, all of which are usually abortive and inseparable from the column. Traces of them may occasionally be met with in the form of tubercles or wing-like processes from the column. In Cypripedium, while the ordinary stamen of the outer row is deficient, two of the inner series are present. The diagram, fig. 192, will serve to show the arrangement of the parts as above described. + represents the situation of the stem or axis; on the opposite side is the bract; between these are placed the sepals, one posterior or next the axis (incorrectly numbered 2 in the plan), two lateral 1, 1; next in order follow the petals, 2, 2, 2, two lateral and somewhat posterior, one larger (the lip), anterior; the outer series of stamens are represented by A 1, A 2, A 3, the two latter being fused with the labellum; a 1, a 2, a 3 represent the position of the inner verticil of stamens, while s, s, s denote the three carpels. It is foreign to the purpose of this book to detail the varied evidence in support of this explanation of the homologies of orchid flowers.[438] All that can be done in these pages is to set forth the evidence furnished by teratology as to this matter—evidence for the most part accumulated and recorded without any special reference to any theory of orchid structure.

The following details all refer to flowers in which the number of stamens in orchidaceous plants was increased beyond what is necessary. They are arranged with reference to the number of adventitious organs, beginning with those in which the number was smallest, and proceeding thence to those in which it was greatest. In some cases it has not been possible to ascertain whether the adventitious organs were really restorations of the numerical symmetry, substitutions of one part for another, stamen for petal, &c., or wholly adventitious productions. Unless otherwise stated, the interpretation put upon the facts thus recorded is that of the present writer, and not necessarily that of the original observer.

Mr. J. T. Moggridge has described and figured a flower of Ophrys insectifera in which there was a vestige of a second stamen present, probably one of the inner series fig. 192 (a^2).[439] The same observer also records the presence of a second anther between the lobes of the normal one. This can hardly be referred to either of the typical stamens, but would seem to be a perverted development of the rostellum.[440]

Roeper is stated by Cramer[441] to have seen a specimen of Orchis morio with two stamens.

In a flower of Habenaria chlorantha, described by the late Professor Henslow,[442] the outer three stamens are suppressed, while two of the inner group are present, as happens normally in Cypripedium.

A flower of Cattleya violacea afforded a similar illustration; but in this case only one of the inner stamens was developed, and this in the form of a small petal, partly adherent to the column.

In Dendrobium normale, Falconer, not only is the perianth regular, but the column is triandrous,[443] the three stamens (according to the diagram of its structure given by Lindley) pertaining to the outer row.

In a specimen of Dendrobium hoemoglossum kindly forwarded from Ceylon by Mr. Thwaites there were three stamens present, of which one posterior belonged to the outer series A 1, and two lateral to the inner a 1, a 2, fig. 192.

M. His observed, several years in succession, some flowers of a species of Ophrys with three sepals, no lateral petals, one lip, and three perfect stamens. In this case probably the two supernumerary stamens were petals which had assumed an anther-like character.

Wydler describes a flower of Ophrys aranifera in which one outer and two inner stamens were present.[444] I have myself met with three such flowers in the same species. The stamens present were A 1, a 1, a 2.

Dr. J. E. Gray exhibited at the Botanical Society of London, in August, 1843, a specimen of Ophrys apifera with a triandrous column, the supernumerary anthers belonging, apparently, to the inner whorl.

In his 'Catalogue of the Plants of South Kent,' p. 56, tab. iv, f. 16, the Rev. G. E. Smith describes and figures a flower of O. aranifera with a triandrous column, seemingly of the same kind as that spoken of by Dr. Gray.

Mr. Moggridge met with a triandrous flower in the same species, and refers the appearance to "a fusion of two flowers, accompanied by suppression and modification."[445] As, however, no details are given in support of this opinion, it may be conjectured that the two additional stamens were members of the inner whorl a 1, a 2, and thus the conformation would be the same as in the flowers just mentioned. The figures given by Mr. Moggridge bear out this latter view, while they lend no support to the hypothesis advanced by him. Nevertheless, no decided opinion can be pronounced by those who have not had the opportunity of examining the flowers in question.

Alphonse de Candolle[446] figures a flower of Maxillaria in exactly the same condition, so far as the stamens are concerned, as in the Ophrys flowers just mentioned. It is curious to observe that in many of these cases the two lateral petals are suppressed.

Von Martius mentions the occurrence of three anthers (naturaliter conformatae) in Orchis morio.[447] Richard, as cited by Moquin-Tandon, Lindley, and others, describes and figures a peloria of Orchis latifolia with regular triandrous flowers.[448]

The writer has examined, in the Royal Gardens at Kew, a flower of Cattleya crispa in which were three stamens, the central one normal; the two lateral ones, belonging probably to the inner whorl, were in appearance like the lateral petals, and one of them was adherent to the central perfect column. Duchartre[449] mentions a flower of Cattleya Forbesii in which there were two labella in addition to the ordinary one, the column being in its normal condition. From the analogy of other cases it would appear as if the additional labella in this instance were the representatives of two stamens of the outer whorl. Beer likewise has put on record the existence of a triandrous Cattleya.[450]

A specimen of Catasetum eburneum forwarded by Mr. Wilson Saunders was normal so far as the sepals and two lateral petals were concerned, but the anterior petal or labellum was flat and in form quite like the two lateral ones; the column was normal and in the situation of the two anterior stamens of the outer series A 2, A 3, were two labella of the usual form (fig. 156, p. 291). Perhaps the Oncidium represented at p. 68, fig. 29, may also be explained on the supposition that the two lateral lobes of the labellum in this flower were the representatives of stamens.

In Fig. 193 is shown the arrangement of parts in a flower of Ophrys aranifera. Here there were three sepals, two lateral petals, one of which was adherent to the side of the column; the central labellum was seemingly deficient, but there were two pseudo-labella placed laterally in the position of the two antero-lateral stamens of the outer series (A 2, A 3). Within these was another perfect stamen occupying the position of the anterior stamen of the inner series (a 3). In another flower of the same species, gathered at the same time (fig. 194), there were three sepals not at all different from those of the normal flower. The three petals next in succession were also, in form and position, in their ordinary state. In colour, however, the two upper lateral petals differed from what is customary, in having the same purplish-brown tint which characterises the lip. Within these petals, at the upper part of the flower, there was the ordinary column, and at the opposite side, alternating with the petals before mentioned, two additional lip-like petals, one provided with a half-anther containing a single perfectly formed pollen-mass (A 2, A 3). It is, perhaps, worthy of notice that the arrangement of the coloured spots on the true labellum, and that on the adventitious lips, replacing the two lower of the outer stamens, were not of a similar character. The supernumerary lips had the [Greek: pi]-shaped marking which is so common in this species, while the true lip was, as to its spots, much more like O. apifera. Alternating with this last whorl were three columns, all apparently perfectly formed and differing only from the ordinary one in their smaller size and corresponding to a 1, a 2, a 3. The ovary in this flower was two-celled, with four parietal placentas, thus giving an appearance as though there had been a fusion of two or more flowers associated with suppression and other changes. The position of the supernumerary organs and the absence of any positive sign of fusion in the bracts or other part of the flower, seemed, however, to negative the idea of fusion.[451]





A similar illustration, for a knowledge of which the writer is indebted to the kindness of Professor Asa Gray and Mr. Darwin, occurred in some specimens of Pogonia ophioglossoides collected by Dr. J. H. Paine in a bog near Utica, New York. It will be seen from the following description that these flowers presented an almost precisely similar condition to those of the Ophrys aranifera just mentioned. "The peculiarities of these flowers," writes Professor Gray, "are that they have three labella, and that the column is resolved into small petaloid organs. The blossom is normal as to the proper perianth, except that the labellum is unusually papillose, bearded almost to the base. The points of interest are, first, that the two accessory labella are just in the position of the two suppressed stamens of the outer series, viz. of A2 and A3, as represented in the diagram, fig. 192; and there is a small petaloid body on the other side of the flower, answering to the other stamen, A1. Secondly, in one of the blossoms, and less distinctly in another, two lateral stamens of the inner series (a1 and a2) are represented each by a slender naked filament. There are remaining petaloid bodies enough to answer for the third stamen of the inner series and for the stigmas, but their order is not well to be made out in the dried specimens." It may here be mentioned that Isochilus is normally triandrous.

A tetrandrous flower of Cypripedium has also been recorded.

In Isochilus, according to Cruger, there are often five stamens, and there are several, besides those already mentioned, in which six more or less perfect stamens have been seen—of these the following may be taken as illustrations. A hexandrous flower of Orchis militaris has been recorded by Kirschleger,[452] and in the accompanying diagram (fig. 195), from Cramer,[453] of a monstrous flower of Orchis mascula, there is one perfect stamen of the outer row and two lip-like stamens of the same series, while the inner verticil comprises one perfect and two abortive stamens.



Morren[454] describes some flowers of Orchis morio in which there were three sepals, three petals, and within the latter two other ternary series of petals; this would seem to be a case of petalody of all six stamens. Morren, however, seems to have considered the additional segments as repetitions of the corolline whorl, though he describes a central mass as the column bearing a "souvenir of the anther." Nevertheless, there is no decisive evidence either in his figure or his description in support of his opinion as to the nature of the central mass, which might be a distorted condition of the styles, or, as is more probable, a rudimentary and irregular flower. Morren also describes another flower of the same plant in which there were three sepals, two lateral petals partially lip-like in aspect, a third labellum normal, two additional labella representing the two anterior stamens of the outer whorl, while more or less developed rudiments of the remaining four stamens also exist.