While, in most cases, the supernumerary stamens can, by reason of their relative position, their complete or partial antheriferous nature, be safely referred to one or other of the six stamens, making up a typical orchid flower, there are other specimens in which the additional stamens are altogether adventitious, and do not admit of reference to the homologue. Thus it was in a specimen of Odontoglossum Alexandrae examined by the writer, and in which, within a normally constructed perianth, there were six columns, all polliniferous, but arranged in so confused and complicated a manner that it was impossible to make out any definite relation in their position. There was nothing to indicate a fusion of flowers, but rather an extension of the centre of the flower, and consequent displacement of the stamens, &c. Again, the existence of adventitious stamens does not necessarily imply the development of organs usually suppressed, inasmuch as they may result from the assumption by the lateral petals of staminal characteristics.

Nevertheless, as far as teratology is concerned, specimens may be found in which some or all of the usually suppressed stamens of Orchidaceae may be found. These stamens may be all perfect (polliniferous), or, as is more frequently the case, more or less petal-like. Moreover, when the stamens are petalodic, the form assumed is usually that of the labellum.

The presence of stamens in undue numbers in orchids is very generally, but not always, attended by some coincident malformation, of which the most frequent is cohesion of two or more sepals, and consequent displacement or adhesion of one petal to the side of the column. Petalody of the styles and median prolification are also sometimes found in association with an augmented number of stamens.



Pleiotaxy of the gynoecium.—An increase in the number of whorls of which the pistil consists is not of very frequent occurrence. Generally after the formation of the whorl of carpels, the energy of the growing point ceases, or if by chance it be continued, the result is more generally the production of a new flower-bud (median prolification) than the repetition of the carpellary series. It is necessary also to distinguish between the veritable augmentation of the pistil and the semblance of it, brought about by the substitution of carpels for some other organs, as pistillody of the stamens, and even of the segments of the perianth, is not very unfrequent, as has already been stated under the head of substitution. Again, the increased number of carpels which is sometimes met with in such flowers, as Magnolia or Delphinium, where the ovaries are arranged in spiral series, is not strictly referable to the present category.

The orange is one of the plants most frequently subject to an augmentation in the number of carpellary whorls; sometimes this is due to the stamens assuming the guise of carpels, but at other times the increase occurs without any alteration in the stamens or other organs. If the adventitious carpels be exposed, they are covered with yellow rind, while those portions that are covered by the primary carpels are destitute of rind. Some varieties of the double tulip are very subject to a similar change, but, in this case, the petals and the stamens very frequently become more or less carpellary in their nature. Fig. 196 represents an increased number of whorls of carpels in the variety called "rex rubrorum," the segments of the perianth having been removed.

In the St. Valery apple, already referred to, there is a second whorl of carpels above the first, a fact which has been made use of to explain the similar structure of the pomegranate.

The tomato (Lycopersicum esculentum) is another plant in which an adventitious series is frequently produced, and generally in combination with the primary series.

In the Chinese primrose (Primula sinensis) a supernumerary whorl is frequently met with, generally associated with other changes in the construction and arrangement of the parts of the flower.

M. de Candolle[455] mentions a flower of Gentiana purpurea with four carpels in one series, and five others in the circle immediately above them. Wigand[456] alludes to an instance wherein there was a second pair of carpels above the first in Vinca herbacea. Dr. Sankey has forwarded flowers of a Pelargonium having a double series of carpels, eight in the outer row, five in the inner, and this condition is stated to exist in the flowers of the same plant for two years consecutively. In Aquilegia I have met with a similar increase in the whorls of carpels.[457] Meissner records a similar augmentation in Polygonum orientale.[458]

Wigand[459] describes and figures a flower of Vinca minor, in which there were two carpels intervening between the ordinary pair, and a similar illustration has been observed by the writer in Allamanda cathartica. Eichler[460] has put on record a similar case in a capparid.

Marchand[461] mentions a polycarpellary berberid (Epimedium Musschianum). The supernumerary carpels in this flower were placed on a short axis, which originated in the axils of the stamens, and as these latter organs were present in their usual number and position, the adventitious carpels could not be considered as resulting from a transformation, or substitution of carpels for stamens.

Lastly, the instance cited by Dr. Allman[462] in Saxifraga Geum may be alluded to. Here there was a row of adventitious carpels between the stamens and pistils, the backs of the carpels being turned towards the axis of the flowers. Dr. Allman explains the presence of the supernumerary parts by the supposed production of a whorl of secondary axes between the stamens and the centre of the flower. These axes are further supposed to bear imperfect flowers, of which the additional carpels are the only traces, but this explanation seems forced.

In addition to the references already cited the following may be given:

Duchartre, 'Ann. Sc. Nat.,' 4 ser., vii, p. 23 (Tulip).

Ferrari, 'Hesperides,' pp. 271, 395, 405. Duchartre, 'Ann. Sc. Nat.,' 4 ser., 1844, vol. i, p. 294. Maout, 'Lecons Element.,' vol. ii, pp. 488-9. Clos, 'Ann. Sc. Nat.,' 1865, p. 317 (Citrus Aurantium).

Clos, 'Bull. Soc. Bot. Fr.,' vol. xiii; 'Rev. Bibl.,' p. 75. Pasquale, 'Reddicont Accad. Sc. Fis. e Math. Napoli.' Octr. 1866 (Solanum Lycopersicum).

On the general subject of multiplication, in addition to previous citations, the reader may be referred to A. P. de Candolle, 'Theorie Element. Bot.,' ed. 3, p. 89.

Increased number of flowers in an inflorescence.—This happens generally as a result of over luxuriant growth, and scarcely demands notice here, being rather referable to variation than to malformation. The increased number of florets in the spikelets of some grasses has already been alluded to (p. 351). Thus spikelets of wheat occasionally produce more than the three florets which are proper to them.[463] It will be remembered that in this as in many other grasses there are rudimentary florets, and it is no matter for surprise that these florets should occasionally be fully developed.

FOOTNOTES:

[392] 'Bull. Soc. Bot. Fr.,' vol. vii, 1860, p. 587.

[393] 'Fragment. Phyt. Austral.,' part xx, p. 270.

[394] 'Bull. Acad. Belg.,' xvi, pt. i, p. 60, "Fuchsia," p. 125, c. ic.

[395] "Theorie de la feuille," 'Arch. des Sciences Bibl. Univers.,' 1868.

[396] See Engelmann, 'De Antholysi,' p. 16, section 12.

[397] Verhandl. des Botanisch. Vereins Brandenburg,' 1859, 1 heft.

[398] See Henslow. 'Mag. Nat, Hist.' 1832, vol. v, p. 429.

[399] 'Phytologist,' September, 1857.

[400] Seemann's 'Journal of Botany,' iv, p. 168, t. 47, f. 3.

[401] 'Illust. Hortic.,' 1866, misc., p. 97.

[402] See Fresenius, 'Mus. Senkenb.,' bd. 2, p. 43. Schlechtendal, 'Bot. Zeit.,' iv, pp. 403, 492, Veronica tetrandra.

[403] 'Flora,' 1865, tab. 6, fig. 8.

[404] 'Org. Veget.,' t. i, p. 497, pl. 42, f. 3.

[405] 'El. Ter. Veg.,' p. 354.

[406] Cited in "Rev. Bibl." of 'Bull. Soc. Bot. Fr.,' 1866, p. 171.

[407] Loc. cit., 351.

[408] 'Mem. Acad. Toulous.,' vi, 1862, ex 'Bull. Soc. Bot. Fr.,' "Rev. Bibl.," vol. ix, 1862. p. 127.

[409] 'Flora.' 1857. p. 289.

[410] L. c., p. 354.

[411] Giraud, 'Ed. Phil. Mag.,' Dec., 1839.

[412] See Cerasus Caproniana, D. C. 'Plant. Rar. Hort. Genev.,' tab. 18.

[413] Nees, 'Linnaea,' v, p. 679, tab. 11 (Schoenodorus).

[414] 'Gard. Chron.,' 1852, p. 452.

[415] See Cramer, 'Bildungsabweich.' pp. 16, 24.

[416] 'Linnaea,' 1842, p. 389, c. ic.

[417] Seemann's 'Journal of Botany,' 1867, vol. v, p. 158.

[418] Cramer, 'Bildungsabweich,' p. 66, Astrantia major, Eryngium, to which may be added Daucus, Heracleum, &c.

[419] See also Reinwardt, 'Nov. Act. Acad. Nat. Cur.,' 12, 1, 37; and Masters, 'Journ. Linn. Soc.,' vi, p. 24.

[420] 'Organog. Veget.,' tab. 53.

[421] 'Missbild.,' p. 206.

[422] Ehrenberg, 'Flora,' 1846, p. 704.

[423] 'Flora,' 1860, tab. 7.

[424] 'Ann. Sc. Nat.,' 3 ser., t. x, p. 207.

[425] 'Mem. Mus.,' xii. t. 17.

[426] 'Nov. Act. Acad. Nat. Cur.,' xv, tab. xxviii, f. 3; 'Bot. Mag.,' t. 1622. "Caryophyllus spicam frumenti referens." A similar malformation in Dianthus barbatus is not uncommon. It has lately been introduced into gardens under the name of Dianthus "mousseux," but is not likely to find favour with gardeners.

[427] 'Bull. Soc. Bot. France,' t. vi, 1859. p. 268.

[428] Weber, 'Verhandl. Nat. Hist. Vereins. Rhein. Pruss.,' 1860.

[429] 'Bot. Zeit.,' 1848, p. 217.

[430] 'De Anthol.,' p. 17, Sec. 12.

[431] 'Linnaea,' vol. ii, 1827, p. 85.

[432] 'De Antholysi,' p. 17, tab. iii, f. 15, 16; Weinmann, 'Phytanth. iconogr.,' nro. 292.

[433] See Hildebrand, 'Bot. Zeit.,' 1862, p. 209, tab. viii; Cramer, 'Bildungsabweich.,' p. 7, tab. xiii; Engelmann, 'De Antholysi,' p. 18, &c. For similar changes in Gagea arvensis see Wirtgen, 'Flora,' 1838, t. xxi. p. 350, and 'Flora.' 1846, p. 353. Some of these are cases of synanthy.

[434] Schlechtendal, 'Bot. Zeit.,' xx, 1862, p. 301.

[435] 'Phil. Bot.,' Sec. 126.

[436] C. Morren, 'Bull. Acad. Belg.,' xix, part ii, p. 17.

[437] 'Seemann's Journal of Botany,' iii, p. 354.

[438] On this point the reader will find an excellent summary in Lindley's 'Vegetable Kingdom,' cd. iii, p. 183a, and in Darwin, 'Fertilisation of Orchids,' p. 292. See also Crueger,'Journ. Linn. Soc.,' t. viii, p. 134.

[439] 'Seemann's Journal of Botany,' vol. iv, p. 168, tab. 47.

[440] Ibid., t. iv. 1866, p. 168, t. xlvii, f. 1.

[441] 'Bildungsabweich,' p. 8; see also 'Bot. Zeit.,' 1852, p. 425.

[442] 'Journ. Linn. Soc.,' t. ii, p. 104. tab. 1, fig. B.

[443] Lindl., "Orchid. Ind.," 'Jour. Linn. Soc.,' iii, p. 9.

[444] 'Arch. Bot.,' ii, p. 300, tab. xvi, f. 11.

[445] 'Seemann's Journal of Botany,' v, p. 318, tab. lxxii, figs. A 4, 4 a.

[446] "Monstr. Veg.," in 'Neue Denkschrift,' p. 17, tab. vii.

[447] 'Flora,' t. viii, 1825, p. 736.

[448] 'Mem. Soc. d'Hist. Nat.,' ii, 1, p. 212, tab. iii.

[449] 'Bull. Soc. Bot. Fr.,' t. vii, 1860, p. 26.

[450] 'Beitr. Morphol. und Biol. Orchid.,' quoted by Cramer; 'Bildungsabweich,' p. 9.

[451] Masters, 'Journ. Linn. Soc.,' viii, p. 207. See also Rodigas, 'Bull. Soc. Bot. Belg.,' iv, p. 266, for similar changes in Cypripedium Hookerae.

[452] Kirschleger, 'Flora,' 1844, p. 131.

[453] 'Bildungsabweich,' p. 11, tab. xiv, f. 3.

[454] 'Bull. Acad. Roy. Belg.,' t. xix, part 2, p. 171.

[455] 'Organogr. Veget.,' t. i, p. 509, tab. 40, figs. 6, 7.

[456] 'Flora,' 1856, p. 715.

[457] 'Linn. Trans.,' t. xxiii, p. 364, tab. 34, fig. 5.

[458] 'Monog. Polygon,' pl. 3, K. f. 12.

[459] 'Flora,' 1856, tab. viii.

[460] Ibid., 1865, tab. ix, f. 6.

[461] 'Adansonia,' vol. iv, 1864, p. 127.

[462] 'Ann. Nat. Hist.,' 1845, vol. xvi, p. 126.

[463] See Schlechtendal, 'Bot. Zeit.,' t. xviii, p. 381 (Triticum); also 'Flora,' t. xiv, 1831, p. 5 (Avena).



PART II.

DIMINISHED NUMBER OF ORGANS.

A diminution in the number of parts is generally due to suppression, using that word as the equivalent of non-development. It corresponds thus in meaning with the Fehlschlagen of the Germans, the avortement complete of Moquin and other French writers. It differs from atrophy, or partial abortion, inasmuch as the latter terms apply to instances wherein there has been a partial development, and in which evolution has gone on to a certain extent, but has, from some cause or other, been checked. These cases will be found under the head of diminished size of organs. As the word abortion is used by different authors in different ways, it is the more necessary to be as precise as possible in the application of the term. In the present work abortion is used to apply to cases wherein parts have been formed, but wherein growth has been arrested at a certain stage, and which, therefore, have either remained in statu quo, while the surrounding parts have increased, or have, from pressure or other causes, actually diminished in size.

In practice, however, it is not always possible to discriminate between those instances in which there has been a true suppression, an absolute non-development of any particular organ, and those in which it has been formed, and has grown for a time, but has afterwards ceased to do so, and has been gradually obliterated by the pressure exercised by the constantly increasing bulk of adjacent parts, or possibly has become incorporated with them. In the adult flower the appearances are the same, though the causes may have been different.



CHAPTER I.

SUPPRESSION OF AXILE ORGANS.

Absolute suppression of the main axis is tantamount to the non-existence of the plant, so that the terms "acaulescent," "acaulosia," etc, must be considered relatively only, and must be taken to signify an atrophied or diminished size of the stem, arising from the non-development of the internodes.

The absence of lateral branches or divisions of the axis is of frequent occurrence, and is dependent on such causes as the following:—deficient supply of nutriment, position against a wall or other obstacle, close crowding of individual plants, too great or too little light, too rich or too poor a soil, &c.

Probably the absence of the swollen portion below the flower in the case of many proliferous roses, double-flowered apples, as already referred to, may be dependent on the non-development of the extremity of the peduncle or flower-stalk. Thus, in a double-flowered apple recently examined, there was a sort of involucel of five perfect leaves, then five sepals surrounding an equal number of petals, numerous stamens, and five styles, but not a trace of an expanded axis, nor of any portion of the carpels, except the styles. The views taken as to the nature of this and similar malformations must depend on the opinion held as to the nature of inferior pistils, and on the share, if any, that the expanded axis takes in their production. As elsewhere said, the evidence furnished by teratology is conflicting, but there seems little or nothing to invalidate the notion that the end of the flower-stalk and the base of the calyx may, to a varying extent, in different cases, jointly be concerned in the formation of the so-called calyx-tube and of the inferior ovary. Obviously it is not proper to apply to all cases where there is an inferior ovary the same explanation as to how it is brought about.

As these pages are passing through the press, M. Casimir de Candolle has published a different explanation as to the nature of the hip of the rose, having been led to his opinion by the conclusion that he has arrived at, that the leaf is to be considered in the light of a flattened branch, whose upper or posterior surface is more or less completely atrophied.

According to M. de Candolle, the calyx-tube, in the case of the rose, is neither a whorl of leaves, nor a concave axis in the ordinary sense in which those terms are used, but is rather to be considered as a ring-like projection from an axis arrested in its ulterior development. The secondary projections from the original one correspond to an equal number of vascular bundles, and develope into the sepals, petals, stamens, and ovaries. If these organs remained in a rudimentary condition, the tube of the calyx would be reduced to the condition of a sheathing leaf. The rose flower, then, according to M. de Candolle, may be considered as a sheathing leaf, whose fibro-vascular system is complete, and from which all possible primary projections are developed.[464]

If, as M. de Candolle considers, the leaf and the branch differ merely in the fact that the vascular system is complete in the latter, and partly atrophied in the former, it would surely be better to consider the "calyx-tube" of the rose as a concave axis rather than as a leaf, seeing that he admits the fibro-vascular system to be complete in the case of the rose.

With reference to this point the reader is referred to Mr. Bentham's account of the morphology and homologies of the Myrtaceae in the 'Journal of the Linnean Society,' vol. x, p. 105. See also ante, pp. 71, 77.

Some doubts also exist as to the nature of the beak or columella of such fruits as those of Geraniaceae, Malvaceae, Umbelliferae, Euphorbiaceae, &c. The nature of the organ in question may probably be different in the several orders named; at any rate the subject cannot be discussed in this place, and it is mentioned here because, now and then, it happens that the organ in question is completely wanting, and hence affords an illustration of suppression.

FOOTNOTES:

[464] 'Theorie de la feuille.' p. 24.



CHAPTER II.

SUPPRESSION OF FOLIAR ORGANS.

This subject may be considered, according as the separate leaves of the stem or of the flower are affected, and according as either the number of members of distinct whorls, or that of the whorls themselves, is diminished.

The terms aphylly, meiophylly, and meiotaxy may be employed, according as the individual leaves are altogether wanting, or with reference to the diminished number of parts in a whorl, or a decrease in the verticils.

Aphylly.—Entire suppression of the leaves is a rare phenomenon. Under ordinary circumstances it occurs in most Cactaceae, in some of the succulent Euphorbias, and other similar plants, where the epidermal layers of the stem fulfil the functions of leaves. But even in these plants leaf-like organs are present in some stage or another of the plant's life.

Partial suppression of the leaf occurs sometimes in compound leaves, some or other of the leaflets of which are occasionally suppressed. Sometimes, as Moquin remarks, it is the terminal leaflet which is wanting, when the appearance is that of Cliffortia, at other times the lateral leaflets are deficient, as in Citrus or Phyllarthron. Ononis monophylla and Fragaria monophylla may be cited as instances of the suppression of the lateral leaflets. If the blade of the leaf disappears entirely, we have then an analogous condition to that of the phyllodineous acacias.

With reference to the strawberry just mentioned, Duchesne, 'Hist. Nat. Frais.,' p. 133, says that this was a seedling raised from the fraisier des bois, and the characters of which were reproduced by seed, and have now become fixed. The monophyllous condition has been considered to be the result of fusion of two or more leaflets, but however true this may be in some cases, it is not the case with this strawberry. M. Paillot states that he has found the variety in a wild state.[465]

In like manner varieties of the following plants occur with simple leaves, Rosa berberifolia (Lowea), Rubus Idaeus, Robinia pseudacacia, Fraxinus excelsior, Sambucus nigra, Juglans nigra, &c.

In one instance seen by the writer every portion of the leaf of a rose was deficient, except the stipules and a small portion of the petiole. (See abortion.)

Meiophylly.—A diminished number of leaves in a whorl occasionally takes place; thus, in some of the Stellatae, and frequently in Paris quadrifolia, the number of leaves in the verticil is reduced. Care must be exercised in such instances that an apparent diminution arising from a fusion of two or more leaves be not confounded with suppression.

Meiophylly of the calyx or perianth.—A lessened number of sepals is not a very common occurrence among dicotyledonous plants. Seringe figures a proliferous flower of Arabis alpina with two sepals only, and a similar occurrence has been noticed in Diplotaxis tenuifolia.

In Cattleya violacea the writer has met with a flower in which the uppermost sepal was entirely wanting, while two of the lateral petals were fused together. Moquin records that in some of the flowers of Chenopodiaceae, in which the inflorescence is dense, a suppression of two or three sepals sometimes occurs. The species mentioned are Ambrina ambrosioides, Chenopodium glaucum, and Blitum polymorphum.

Meiophylly of the corolla.—Suppression of one or more petals is of more frequent occurrence than the corresponding deficiency in the case of the sepals. Among Caryophyllaceae imperfection as regards the numerical symmetry of the flower is not uncommon, as in species of Cerastium, Sagina, Dianthus, &c. In Ranunculaceae the petals are likewise not unfrequently partially or wholly suppressed. A familiar illustration of this is afforded by Ranunculus auricomus, in which it is the exception to find the corolla perfect.[466] Some varieties of Corchorus acutangulus in west tropical Africa are likewise subject to the same peculiarity. Amongst Papilionaceae absence of the carina or of the alae is not uncommon, as in Trifolium repens, Faba vulgaris, &c.

Moquin relates a case of the kind in the haricot bean, in which the carina was entirely absent, and another in the pea, where both carina and alae were missing, thus reducing the flower to the condition that is normal in Amorpha and Afzelia. Suppression of the upper lip in such flowers as Calceolaria has been termed by Morren "apilary."

In Orchidaceae entire absence of the labellum, frequently without any other perceptible change, is of common occurrence. The writer has seen numerous specimens of the kind in Ophrys apifera and O. aranifera; also in Dendrobium nobile, AErides odoratum, Cypripedium villosum, Listera ovata, &c. Morren[467] mentions analogous deficiencies in Zygopetalum maxillare, Calanthe sp., and Cattleya Forbesii. In most of these there was also a fusion of the two lower sepals, which were so twisted out of place as to occupy the situation usually held by the labellum. At the same time the column was partially atrophied. To this deficiency of the lip the author just quoted proposed to apply the term acheilary, [Greek: a-cheilarion]. Mr. Moggridge has communicated to the author an account of certain flowers of Ophrys aranifera, in which the petals were deficient, sometimes completely, at other times one or two only were present.

Meiophylly of the androecium.—Suppression of one or more stamens, independently of like defects in other whorls, is not uncommon, even as a normal occurrence, e.g. in Carlemannia, where the flower, though regular, has only two stamens, and other similar deficiencies are common in Dilleniads.

Seringe relates the occurrence of suppression of some of the stamens in Diplotaxis tenuifolia,[468] St. Hilaire in Cardamine hirsuta, others in C. sylvatica.

In Caryophyllaceae suppression of one or more stamens has been observed in Mollugo cerviana, Arenaria tetraquetra, Cerastium, &c.[469] Among violets the writer has observed numerous flowers in which two or three stamens were suppressed. Chatin[470] alludes to a similar reduction in Tropaeolum, while in flowers that are usually didynamous absence of two or more of the stamens is not unfrequent, e.g. in Antirrhinum, Digitalis, while in a flower of Catalpa a solitary perfect stamen, and a complete absence of the sterile ones usually present, have been observed. This might have been anticipated from the frequent deficiencies in the staminal whorl in these plants under what are considered to be normal conditions. Reduction of the staminal whorl is also not unfrequent in Trifolium repens and T. hybridum, and has been seen in Delphinium, &c.[471]

Meiophylly of the gynoecium.—Numerical inequality in the case of the pistil, as compared with the other whorls of the flower, is of such common occurrence, under ordinary circumstances, that in some text-books it is looked on as the normal condition, and a flower which is isomerous in the outer whorls is by some writers not considered numerically irregular if the number of the carpels does not coincide with that of the other organs.

But in this place it is only necessary to allude to deviations from the number of carpels that are ordinarily found in the particular species under observation. As illustrations the following may be cited:—Arenaria tetraqueta, which has normally three styles, and a six-valved capsule, has been seen with two styles, and a four or five-valved capsule. Moquin relates an instance in Polygala vulgaris where there was but a single carpel, a condition analogous to that which occurs normally in the allied genus Mozinna. Reseda luteola occasionally occurs with two carpels only, while Aconites, Delphiniums, Nigellas, and Paeonies frequently experience a like diminution in their pistil.

In a flower of Papaver Rhaeas the writer has recently met with an ovary with four stigmas and four parietal placentae only, and to Mr. Worthington Smith he is indebted for sketches of crocus blooms with two, and in one instance only a solitary carpel.

Moquin cites the fruit of a wild bramble (Rubus) in which all the little drupes which go to make up the ordinary fruit were absent, except one, which thus resembled a small cherry. In Crataegus the pistil is similarly reduced to a single carpel, as in C. monogyna.

The writer has on more than one occasion met with walnuts (Juglans) with a single valve and a single suture.[472] If the ovary of Juglans normally consisted of two valvate carpels, the instances just alluded to might possibly be explained by the suppression of one carpel, but the ovary in Juglans is at first one-celled according to M. Casimir de Candolle.

Among monocotyledons Convallaria majalis may be mentioned as very liable to suffer diminution in the number of its carpels, either separately or in association with other changes.[473]

Meiophylly of the flower as a whole.—In the preceding sections a reduction in the parts of each individual whorl has been considered without reference to similar diminution in neighbouring verticils. It more commonly happens, nevertheless, that a defect in one series is attended by a corresponding imperfection in adjoining ones. Thus trimerous fuchsias and tetramerous jasmines may frequently be met with, and Turpin describes a tetramerous flower of Cobaea scandens. Perhaps monocotyledonous plants are more subject to this numerical reduction of the parts of several verticils than are other flowering plants. Thus, in both Lilium lancifolium and L. auratum the writer has frequently met with pentamerous flowers. In Convallaria maialis a like deviation not unfrequently occurs.[474] M. Delavaud has recorded a similar occurrence in a tulip.[475]

Dimerous crocuses may also sometimes be met with. In one flower of this nature the segments of the perianth were arranged in decussating pairs, and the four stamens were united by their filaments so as to form two pairs.

M. Fournier mentions something of the same kind in the flower of an Iris.[476]

Orchids seem peculiarly liable to the decrease in the number of their floral organs. Prillieux[477] mentions a flower of Cattleya amethystina wherein each whorl of the perianth consisted of two opposite segments.

The same observer has put on record instances of a similar kind in Epidendrum Stamfordianum. In one flower of the last-named species the perianth consisted of one sepal only, and one lip-like petal placed opposite to it.[478] Morren[479] describes a flower of Cypripedium insigne, in which there were two sepals and two petals. Of a similar character was the flower found by Mr. J. A. Paine, and described in the following terms by Professor Asa Gray in the 'American Journal of Science,' July, 1866:—"The plant" (Cypripedium candidum) "bears two flowers: the axillary one is normal; the terminal one exhibits the following peculiarities. The lower part of the bract forms a sheath which encloses the ovary. The labellum is wanting; and there are two sterile stamens, the supernumerary one being opposite the other, i.e. on the side of the style where the labellum belongs. Accordingly the first impression would be that the labellum is here transformed into a sterile stamen. The latter, however, agrees with the normal sterile stamen in its insertion as well as in shape, being equally adnate to the base of the style. Moreover, the anteposed sepal is exactly like the other, has a good midrib and an entire point. As the two sterile stamens are anteposed to the two sepals, so are the two fertile stamens to the two petals, and the latter are adnate to the style a little higher than the former. The style is longer than usual, is straight and erect; the broad, disciform stigma therefore faces upwards; it is oval and symmetrical, and a light groove across its middle shows it to be dimerous. The placentae, accordingly, are only two. The groove on the stigma and the placentae are in line with the fertile stamens.

Here, therefore, is a symmetrical and complete, regular, but dimerous orchideous flower, the first verticil of stamens not antheriferous, the second antheriferous, the carpels alternate with these; and here we have clear (and perhaps the first direct) demonstration that the orchideous type of flower has two stamineal verticils, as Brown always insisted."



Dr. Moore, of Glasnevin, kindly forwarded to the writer a flower of Calanthe vestita (fig. 198), in which there were two sepals only, anterior and posterior, and two petals at right angles to the two sepals. The lip was entirely wanting, but the column and ovary were in their usual condition. In Odontoglossum Alexandrae a similar reduction of parts has been observed by the author (fig. 199).

It is curious to observe in these flowers how precisely one sepal occupies the position of the labellum, and how the lateral petals are displaced from the position they usually occupy, so as to form a regular flower, the segments of which decussate, thus giving rise to a species of regular peloria.

The genus Maelenia was established on a malformed flower of Orchis of similar character to those above mentioned.

Meiotaxy of the calyx.—As already mentioned, this term is here employed to denote those illustrations in which entire whorls are suppressed. Complete deficiency of the calyx in a dichlamydeous flower seems seldom or ever to occur; the nearest approach to it would be in those cases where the calyx is, as it is termed, "obsolete," but here it is chiefly the limb of the calyx which is atrophied, the lower portion being more or less adherent to the ovary. In what are termed monochlamydeous flowers both calyx and corolla are wanting, as in Salicineae and many other orders.

Meiotaxy of the corolla.—Deficiency of the entire corolla occurs in conjunction with similar reductions in other organs, or as an isolated phenomenon in the many apetalous varieties of plants recorded in books. Deficiency of the corolla was observed in Campanula perfoliata and Ruellia clandestina by Linne, who calls such blooms flores mutilati.[480] Drs. Hooker and Thomson relate a similar occurrence in Campanula canescens and C. colorata. Some plants seem as a normal occurrence to produce flowers of different construction, and are hence termed dimorphic, as in many Malpighiaceae, Violaceae, Oxalidaceae, in some of the flowers of which the petals are altogether wanting, while in others the corolla is developed as usual. This deficiency of the corolla is frequently, but not invariably, associated with an increased fertility. Thus, in some violets the flowers produced in summer, and in which the petals are either entirely suppressed or are more or less atrophied, are always fertile, while the blossoms developed in spring, and in which the petals are always present, are much less fertile. In Oxalis Acetosella there are two forms of flower, the one with, the other without, petals, but both seem equally fertile. Linne remarks that many plants which, in warm latitudes, produce a corolla, do not do so when grown in colder climates. Thus, certain species of Helianthemum are apetalous in Lapland. In the Pyrenees, according to Bentham, the flowers of Ajuga iva are constantly deprived of their corolla.[481]

Apetalous flowers have been noted most frequently in the following plants:

Aconitum, sp. pl.! Cardamine impatiens. Cheiranthus Cheiri! Viola odorata! Cerastium vulgatum! Alsine media. Stellaria. Lychnis dioica! Dianthus barbatus, and other Caryophylleae. Helianthemum, sp.! Oxalis Acetosella. Balsamineae. Malpighiaceae. Rosa centifolia. arvensis! Crataegus! Medicago lupulina. Melilotus officinalis. Ononis minutissima. Saxifraga longifolia. Verbascum Thapsus. Ajuga iva. Teucrium Botrys. Lamium purpureum! amplexicaule. Polemonium caeruleum. Campanula, sp. pl.! Ruellia clandestina. Lonicera Periclymenum! Tradescantia, sp.! Hymenocallis.

The following references apply some to apetalous and others to dimorphic flowers, but it must be remembered that the latter plants are not necessarily wanting in petals or stamens, &c., though the functional activity of the parts may be impaired:

A. de Jussien, 'Monogr. Malpigh.,' pp. 82, 334. Torrey, 'Fl. New York,' i, p. 428. Hooker and Thomson, 'Journ. Linn. Soc.,' ii, p. 7, Guillemin, 'Archiv. de Botan.,' i, p. 412. Michalet, 'Bull. Soc. Bot. Fr.,' vii. p. 465. Mueller, 'Bot. Zeit.,' 1857, p. 729. 'Natural History Review,' July, 1862, p. 235.

Meiotaxy of the androecium.—Complete suppression of the stamens occurs normally in the female flowers of unisexual plants, and, as an accidental occurrence, is not very uncommon. Erica Tetralix is one of the plants in which this is said to happen. The variety anandra is said to have been known in France since 1635. Cornuti speaks of it in his 'Enchiridion.' In 1860 M. du Parquet discovered it in peaty woods near Nangis (Seine et Marne).

Many Umbelliferae, such as Trinia vulgaris, present a like deficiency, while it is of common occurrence among Rosaceae and Pomaceae. In the latter group the St. Valery apple, so often referred to, is an illustration. To obtain fruits from this variety it is necessary to apply pollen from another flower, a proceeding made the occasion of festivity and rejoicing by the villagers in some parts of France. In some of the Artemisias, especially in Artemisia Tournefortiana, all the florets have been noticed to be female, owing to the suppression of the stamens, and this suppression is associated with a change in the form of florets.[482] Mr. Moggridge has communicated to the author flowers of Thymus Serpyllum from a plant in which all the stamens were deficient, the flower being otherwise normal.

M. Dupont has given a list of nineteen species of Chenopodiaceae in which female flowers are occasionally produced, owing to the entire suppression of the staminal whorl.[483]

Flowers the subjects either of regular or irregular peloria, q. v., are often destitute of some or all their stamens, e.g. Calceolaria, Linaria, Viola, &c., while in cases of synanthy suppression of some of the parts of the flower, and specially of the stamens, is of very common occurrence.

Suppression of the androecium as a teratological occurrence has been most frequently noticed in the following plants, omitting members of those families whose floral construction is normally incomplete in the majority of instances, and exclusive also of cases of substitution. See also under Heterogamy.

Ranunculus Ficaria! auricomus! bulbosus! Cruciferae, sp. pl. Violaceae, sp. pl. Honckenya peploides. Stellaria. Caryophyllaceae, sp. pl. Malpighiaceae, sp. pl. Tropaeolum majus! Fragaria vesca! Rubus, sp. Pyrus Malus. Agrimonia vulgaris. Rosaceae, sp. pl. Trifolium hybridum. repens. Umbelliferae, sp. pl. Onagraceae, sp. pl. Hippuris vulgaris. Callitriche vernalis. autumnalis. Lonicera Periclymenum. Erica Tetralix. Thymus Serpyllum. Calceolaria. Compositae, sp. pl. Chenopodiaceae, sp. pl. Stratiotes aloides.

Meiotaxy of the gynoecium.—Complete suppression of the pistil is of more frequent occurrence than that of the stamens, hence more flowers become accidentally unisexual by suppression of the pistil than by deficiency of the stamens.

In many Umbelliferae, e.g. Torilis Anthriscus, Cicuta virosa, the central flowers are often male, owing to the suppression of the pistil. In many double flowers, owing to the excessive multiplication of petaloid stamens, the pistil is suppressed, in which cases it often happens that the flower is depressed in the centre, as in some garden varieties of Ranunculus. Schlechtendal, in describing a flower of Colchicum autumnale, in which the perianth was virescent, says that, although the stamens were present, the pistil was absent.

In proliferous flowers the pistil is often completely defective, its place being occupied by the adventitious bud or axis.

As in other cases of like nature, suppression of the pistil is very frequently consequent on fusion of flowers or other changes. Thus Morren relates an instance of synanthy in the flowers of Torenia scabra, accompanied by resorption or disappearance of some parts and spiral torsion of others. The pistil was entirely absent in this instance.[484]

M. Gaetano Licopoli places on record an instance where the petals and carpels of Melianthus major were suppressed.[485]

On the whole, the pistil seems less subject to changes of this character than the androecium.

Suppression of the pistil has been most frequently recorded in flowers (normally bisexual) of—

Ranunculus! Aconitium! Delphinium! Paeonia. Caryophylleae! Umbelliferae. Trifolium repens. hybridum. Compositae, sp. pl. Datura. Torenia asiatica. Colchicum autumnale.

Suppression of ovules,—abortion of seeds.—The two cases are taken together, as the effects are similar, though it must be remembered that in the one case the ovules at any rate have been formed, but their development has been arrested, while in the other they have never existed. The precise cause that has determined the absence of seed cannot in all cases be ascertained in the adult condition, hence it is convenient to treat the two phenomena under one head.

Many plants in other than their native climates either produce no fruit at all, or the fruits that are produced are destitute of seed, e.g. Musa, Artocarpus, &c. Some of the cultivated varieties of the grape and of the berberry produce no seeds.

Suppression or abortion of the seed is frequently associated with the excessive development either in size or number of other portions of the plant, or with an altered condition, as when carpels become foliaceous and their margins detached. Hybridisation and cross fertilisation are also well-known agents in diminishing the number and size of seeds.

Meiotaxy of the parts of the flower in general.—In the preceding sections suppression has been considered as it affected individual members of a whorl or separate whorls. It rarely happens, however, that the suppression is limited in this way. More generally several of the parts of the flower are simultaneously affected in the same manner.

A few illustrations are all that is necessary to give as to this point.

One of the most familiar instances is that of the cauliflower or broccoli, where the common flower-stalk is inordinately thickened and fleshy, while the corolla and inner parts of the flower are usually entirely suppressed; the four sepals can, however, generally be detected.

Maximowicz describes a Stellaria (Kraschenikovia) in which the upper flowers are male only, while the lower ones, which ultimately become buried in the soil, have neither petals, stamens, nor styles, but the walls of the capsule are fleshy, and enclose numerous seeds.[486]

Kirschleger[487] mentions a variety of Lonicera Caprifolium, which was not only destitute of petals but of stamens also.

In some species of Muscari and Bellevalia the uppermost flowers of the raceme show more or less complete suppression of almost all the part of which the flower normally consists. In those cases where an imperfect perianth exists, but in which the stamens and pistils are entirely suppressed, Morren applies the term Cenanthy, [Greek: kenos], empty.

Complete suppression of the flower.—It is not necessary in this place to allude to that deficient production of flowers characteristic of what is termed by gardeners a "sky bloomer." In such plants often the requisite conditions are not complied with, and the skill of the gardener is shown in his attempt to discover and allow the plant to avail itself of the necessary requirements. We need here only allude to those instances in which provision is made for the production of flowers, and yet they are not produced. A good illustration of this is afforded by the feather-hyacinth, Hyacinthus comosus, in which the flowers are almost entirely suppressed, while the pedicels are inordinately increased in number, and their colour heightened. Something similar occurs in several allied species, and in Bowiea volubilis. The wig plant (Rhus Cotinus) affords another illustration of the same thing. Some tendrils also owe their appearance to the absence of flowers, being modified peduncles; proofs of this may frequently be met with in the case of the vine.

In Lamium album I have seen one of the verticillasters on one side of the stem completely wanting, the adjacent leaf being, however, as fully formed as usual.

General remarks on suppression.—On comparing together the various whorls of the flower in reference to suppression, and, it may be added, to atrophy, we find that these phenomena occur most rarely in the calyx, more frequently in the corolla, and very often in the sexual organs and seeds; hence it would seem as if the uppermost and most central organs, those most subject to pressure and latest in date of development—formed, that is, when the formative energies of the plant are most liable to be exhausted—are the most prone to be suppressed or arrested in their development. When the plants in which these occurrences happen most frequently are compared together, it may be seen that partial or entire suppression of the floral envelopes, calyx, and corolla, is far more commonly met with in the polypetalous and hypogynous groups than in the gamopetalous or epigynous series.

The orders in which suppression (speaking generally) occurs most often as a teratological occurrence are the following:—Ranunculaceae, Cruciferae, Caryophyllaceae, Violaceae, Leguminosae, Onagraceae, Jasminaceae, Orchidaceae. It will be observed that these are all orders wherein suppression of the whole or part of the outer floral whorls takes place in certain genera as a constant occurrence.

Again, it may be remarked that many of these orders show a tendency towards a regular diminution of the assumed normal number of their parts; thus, among Onagraceae, Circeia and Lopezia may be referred to, the former normally dimerous, the latter having only one perfect petal. So in fuchsias, a very common deviation consists in a trimerous and rarely a dimerous symmetry of the flower.

Although, if the absolute number of genera or orders be counted, there appears to be little difference in the frequency of the occurrence of suppression in irregular flowers as contrasted with regular flowers, yet if the individual instances could be counted in the two groups respectively it would be found that suppression is more common among irregular than in regular flowers. Thus, the number of individual instances of flowers in which the perianth is defective is comparatively large among Violaceae, Leguminosae, and Orchidaceae. This statement hardly admits of precise statistical proof; still, it is believed that any observer who pays attention to the subject must come to the same conclusion. This is but another illustration of the fact that conditions which are abnormal in one plant constitute the natural arrangement in others.

As to the suppressions that occur in the case of the sexual organs, and the relations they bear to dimorphism, diclinism, &c., but little stress has been laid on them in this place, because their chief interest is in a physiological point of view, and is treated of in the writings of Mohl, Sprengel, Darwin, Hildebrand, and others. All that need be said here is, that teratology affords very numerous illustrations of those intermediate conditions which are also found, under natural circumstances, between the absolutely unisexual flowers, male or female, and the structurally hermaphrodite ones. Rudimentary stamens or pistils are of very common occurrence in monstrous flowers. See Chapter on Heterogamy, &c.

FOOTNOTES:

[465] 'Rev. Hortic.,' 1866, p. 467.

[466] De Rochebrune, 'Bull. Soc. Bot. Fr.,' ix, p. 281. The author points out seven grades between complete absence of petals and their presence in the normal number in this plant. See also Gaudin, in 'Koch. Fl. Helv.;' Koch. 'Synops. Fl. Germ.;' Cramer, 'Bildungsabweich,' p. 85.

[467] 'Bull. Acad. Belg.,' t. xix, part 1, p. 255.

[468] 'Bull. Bot.,' i, p. 7, tab. i, f. 7.

[469] See Gay, 'Ann. Sc. Nat.,' iii, p. 27.

[470] 'Ann. Sc. Nat.,' 4 ser., v, p. 305.

[471] Cramer, 'Bildungsabweich,' p. 90.

[472] See also Clos, 'Bull. Soc. Bot. Fr.,' xiii, p. 96, adnot.

[473] See Cramer, 'Bildungsabweich,' p. 7. Hildebrand, 'Bot. Zeit.,' xx, 1862, p. 209.

[474] See Hildebrand, 'Bot. Zeit.,' xx, 1862, p. 209.

[475] 'Bull. Soc. Bot. Fr.,' viii, p. 287.

[476] 'Bull. Soc. Bot. Fr.,' vol. viii, 1861, p. 152.

[477] Ibid., ix, p. 275.

[478] Ibid., 1861, vol. viii, p. 149.

[479] 'Lobelia,' p. 55.

[480] 'Phil. Bot.,' p. 119.

[481] 'Cat. Plant. Pyr,' p. 58.

[482] Moquin-Tandon, loc. cit., p. 328.

[483] For other instances see Chatin in 'Ann. Sc. Nat.,' 4 ser., vol. v, p. 305.

[484] See also Morren. 'Bull. Acad. Belg.,' xv, Fuchsia, p. 67.

[485] Cited in 'Bull. Soc. Bot., France,' t. xiv ("Rev. Bibl."), p. 253.

[486] 'Primit. Flor. Amurens.' p. 57.

[487] 'Flora.' 1848. p. 484.



BOOK IV.

DEVIATIONS FROM THE ORDINARY SIZE AND CONSISTENCE OF ORGANS.

In the animal kingdom the entire adult organism, as well as each of its separate parts, has certain dimensions, beyond which, under ordinary circumstances, it does not pass, either in the one direction or the other. It may not be easy or possible to state what the limits are, but, practically, this inability to frame a precise limitation is productive of no inconvenience. It is universally admitted that a certain animal attains such and such dimensions, and that one organ has a certain proportionate size as contrasted with another. The same rules hold good in the case of plants, though in them it is vastly more difficult to ascertain what may be called the normal dimensions or proportions. Nevertheless observation and experience soon show what may be termed the average size of each plant, and any disproportion between the several organs is speedily detected.

When there is a general reduction in size throughout all the organs of a plant, or throughout all the nutritive organs, stem, leaves, &c., and the several portions participate in this diminished size, we have what are generally termed "dwarf varieties," dwarf in comparison, that is, with the ordinary condition of the plants; on the other hand, if the entire plant, or, at least, if the whole of one set of organs be increased in size beyond the recognised average, we have large varieties, often qualified by such terms as macrophylla, longifolia, macrantha, &c. &c. In all these cases either the entire plant or whole series of organs are alike increased or diminished beyond average limits; and such variations are often very constant, and are transmitted by hereditary transmission. It may be supposed that such deviations may have originated, in the first instance, either from excessive use, or from disuse, or from the agency of certain conditions promoting or checking growth, as the case may be; but whether or no, it is certain that these variations often persist under different conditions, and that they often retain their distinctive characters side by side with plants presenting the normal average dimensions. In other cases the variations in size are of a less general character, and affect certain organs of a whorl in a relative manner, as, for instance, in the case of didynamous or tetradynamous stamens, where two or four stamens are longer than their fellows, the long or short stamens and styles of di- and tri-morphic flowers, &c. These differences are sometimes connected with the development of parts in succession, and not simultaneously.

Teratological deviations of size differ from those of which mention has just been made chiefly in this, that they are more limited in their manifestations. It is not, as a rule, the whole plant, or the whole series of nutritive or of reproductive organs, that are affected, but it is certain parts only; the alteration in size is more a relative change than an absolute one.

For convenience sake the teratological alterations of size may be divided into those which are the result of increased growth and those which arise from diminished action. It will be seen, therefore, that in these instances it is the bulk of the organs that is increased, not their number; moreover, their development or metamorphosis is not necessarily altered. In connection with increased size an alteration of consistence is so frequent that the two phenomena are here taken together. It will be borne in mind that the changes of consistence from membranous to succulent or woody are very frequent in the ordinary course of development. They may also occur as accidental phenomena, or the normal conditions of any particular flower or fruit may be exactly reversed, the usually succulent fruit becoming dry and capsular, and so forth.



PART I.

HYPERTROPHY.

The term hypertrophy may serve as a general one to comprise all the instances of excessive growth and increased size of organs, whether the increase be general or in one direction merely. General hypertrophy is more a variation than a deformity, unless indeed it be caused by insect puncture or the presence of a fungus, in which case the excessive size results from a diseased condition. For our present purpose hypertrophy may be considered as it affects the axile or the foliar organs, and also according to the way in which the increased size is manifested, as by increased thickness or swelling—intumescence, or by augmented length-elongation, by expansion or flattening, or, lastly, by the formation of excrescences or outgrowths, which may be classed under the head of luxuriance or enation.

As size must be considered in this place relatively, it is not possible to lay down any precise line separating what are considered to be the normal dimensions from those which are abnormal.

In practice no inconvenience will be found to accrue from this inability to establish a fixed rule, and we may say that an hypertrophied organ is one which, from some cause or other, attains dimensions which are not habitual to the plant in its usual, healthy, well-formed state.

It will be seen that under this general head of hypertrophy, increase of size, however brought about, is included; thus, not only increase in length, but also in thickness; alterations of substance or consistence, no less than of dimensions, are here grouped together. The alterations of consistence resulting from an inordinate development of cellular, fibrous, or ligneous tissue, are, of course, strictly homologous with the similar changes which occur, under ordinary circumstances, during the ripening of fruits or otherwise.

Hypertrophy, whatever form it may assume, may be so slight as not perceptibly to interfere with the functions of the part affected, or it may exist to such an extent as to impair the due exercise of its office. It may affect any or all parts of the plant, and is generally coexistent with, if not actually dependent on, some other malformation. Thus, the inordinate growth of some parts is most generally attended by deficiency in the size and number of others, as in the peripheral florets of Viburnum or Hydrangea, where the corollas are relatively very large, and the stamens and pistils abortive.



CHAPTER I.

ENLARGEMENT.

A swollen or thickened condition (renflement) is usually the result of a disproportionate formation of the cellular tissue as contrasted with the woody framework of the plant. We see marked instances of it in cultivated carrots and turnips, the normal condition of the roots or root-stocks in these plants being one of considerable hardness and toughness, and their form slender, tapering, and more or less branched.

The disproportionate development of cellular tissue is also seen in tubers and bulbs, and in the swollen stems of such plants as Echinocactus, Adenium obesum, some species of Vitis, &c. So, too, the upper portion of the flower-stalk occasionally becomes much dilated, so as ultimately to form a portion of the fruit. But it is not necessary to give farther illustrations of this common tendency in some organs to become hypertrophied. As a result of injury from insects or fungi, galls and excrescences of various kinds are very common, but their consideration lies beyond the scope of the present work.



Enlargement of axile organs.—All the species of Pelargonium, Geranium, Mirabilis, as well as those of Caryophylleae and other orders, have tumid nodes as a normal occurrence. In the genus Pelargonium this swelling is sometimes not confined to the nodes, but extends to the interspaces between them, e.g. P. spinosum. This condition, which happens as a natural feature in the species just named, may also occur as an exceptional thing in others. The author is indebted to Dr. Sankey for a branch of Pelargonium which was thus thickened, the remaining branches not being in any way affected. The leaves on the swollen branch were smaller than the others, and their stalks more flattened. There was, in this instance, no trace of fungus or insect to account for the swelling of a single branch, which might, therefore, be due to bud-variation, perhaps to reversion to some ancestral form. The repeated cross fertilisations to which Pelargoniums have been subjected render this hypothesis not an improbable one.

As an accompaniment to a spiral torsion of the woody fibres, this distension of the stem is frequently met with, as in Valeriana, Dipsacus, &c. (See Spiral Torsion.)

Knaurs.—On certain trees, such as the oak, the hornbeam, some species of Crataegus, &c., hard woody lumps may occasionally be seen projecting, varying greatly in size, from that of a pea to that of a cocoa-nut. They are covered with bark, and consist in the interior of very hard layers of wood disposed irregularly, so as to form objects of beauty for cabinet-makers' purposes. From the frequent presence of small atrophied leaf-buds on their surface, it would seem as if the structures in question were shortened branches, in which the woody layers had become inordinately developed, as if by compensation for the curtailment in length.[488] The cause of their formation is not known, but it has been ascertained that they are not due to insect agency. Knaurs may occasionally be used for purposes of propagation, as in the case of the "uovoli of the olive" and the "burrs" that are formed on some varieties of apple, from which both roots and leaf-shoots are produced in abundance.

A distinction must be drawn between those instances in which the swelling is solid throughout from the excessive formation of cellular tissue, and those wherein it is hollow from the more rapid growth of the outer as contrasted with the inner portions. These latter cases might be classed under the head of distension.



Enlargement of the buds may be seen in the case of bulbs and tubers. Occasionally these organs are developed in the axils of leaves, when their nature becomes apparent. A swollen bud or bulbil in this situation is not uncommon in some cultivated tulips and lilies. The presence of small tubers in the axils of the leaves in the potato, as shown in fig. 201, is also not unfrequent.



Enlargement of the flower-stalk.—The cauliflower and broccoli afford familiar illustrations of hypertrophy of the flower-stalk, accompanied by a corresponding defective development of the flowers. In the case of the ash the terminal pedicels occasionally become swollen and distorted, while the flowers are completely deficient, as shown in the adjacent cut (fig. 202).

In grapes a similar condition may occasionally be met with in which the terminal pedicels become greatly swollen and fused into a solid mass. It would seem probable that this change is due to insect puncture, or to the effect of fungus growth at an early stage of development, but as to this point there is at present no evidence.[489]



In the apple a dilatation of the flower-stalk below the ordinary fruit may occasionally be observed, thus giving rise to the appearance of two fruits superposed and separated one from the other by a constriction. (See fig. 176, p. 327.) The lower swelling is entirely axial in these cases, as no trace of carpels is to be seen. M. Carriere[490] mentions an instance wherein from the base of one apple projected a second smaller one, destitute of carpels, but surmounted by calyx-lobes as usual. The direction of this supernumerary apple was the exact opposite of that of the primary fruit.



In pears, quinces, and apples, a not uncommon deviation is one in which the axis is prolonged beyond the ordinary fruit, like which it is much swollen. Occasionally the axis is not only prolonged, but even ramifies, the branches partaking of the succulent character of the ordinary pome. Such instances are frequently classed under the head of prolification, but they have in general no claim to be considered in this light, for the reasons already given in the chapter relating to that subject. (See p. 135.)[491]

A very curious illustration of hypertrophy of the flower-stalk is recorded and figured by M. Carriere[492] in the cherry. The calyx in these fruits was completely superior, the succulent portion of the fruit being made up of the dilated extremity of the peduncle, and possibly in part of the base of the calyx. The general appearance was thus that of a crab-apple. There was no stone in the interior, but simply a rudimentary kernel or seed.[493]

Moquin-Tandon records an instance in which the stamens of each individual flower in the inflorescence of a vine were hypertrophied, the sepals, petals, and other organs of the flower, being proportionately diminished.[494]

In this place may also be mentioned the hypertrophied condition of the placenta observed by Alphonse de Candolle in a species of Solanum, and also in a species of Melastoma. Not only was the placenta unusually large in these flowers, but it also protruded beyond the ovary.[495] A similar state of things in Lobelia and Cuphea has already been alluded to under the head of Alterations of Direction (p. 210).

The following singular growth in a tomato is described by the Rev. M. J. Berkeley in the 'Gardeners' Chronicle' for 1866, p. 1217, and appears to have been an extension of the placenta:—"On the first glance it seemed as if an unusually large grape-stone had accidentally fallen on the upper surface of the fruit, and was attached by the narrow base. The process was, however, five lines long, and much narrowed below, besides which, though it was pale green above, the base was coral-red, like the tomato itself. It grew on a narrow and shallow crack on the surface of the fruit, and was found below to communicate directly with a fibro-vascular bundle, which entered into the composition of a portion of the placenta. On making a vertical section, instead of being succulent, as I expected, it was white and spongy within, with several lacunae, and one or two irregular fibro-vascular bundles, with highly developed spiral vessels threading the centre. These vessels, moreover, were tinged with brown, as in many cases of diseased tissues. There was not the slightest appearance of placentae or anything indicating an abortive fruit. On closer examination the cuticle was found to consist of thick-walled cells, exactly like those of the tomato, while the spongy mass consisted of a similar tissue to the fleshy portion of the fruit, but with far less wrinkled walls, and more indistinct intercellular spaces. The most striking point, however, was the immense quantity of very irregular and unequal starch-grains with which they were gorged, which gave a peculiar sparkling appearance to them when seen en masse. I am inclined to regard the body rather as an abortive axis than an undeveloped fruit. In almost all, if not all, these cases of abnormal growth, whether from leaves, petioles, fruit, or other portions of the plant, we find an immediate connection with one or more spiral vessels, which if not existent at first are developed sooner or later. In the present case the connection of the fibro-vascular tissue of the fruit and abnormal growth was plain enough, but whether it existed when the body was first given off I am unable to say, as it was fully developed when the fruit was brought to me."

Enlargement of the leaves.—Increase in the size or substance of leaves takes places in several ways, and affects the whole or only certain portions of them. The simplest form of this malformation is met with in our cabbages, which, by the art of the gardener, have been made to produce leaves of greater size and thickness than those which are developed in the wild form. In such instances the whole substance of the leaf is increased in bulk, and the increase affects the fibrous framework of the leaves as well as the cellular portions, though the exaggerated development of the latter is out of proportion to that of the former.

In some species of Podocarpus there may occasionally be seen at the base of the branchlets a dozen or more fleshy scales, of a rose colour, passing gradually into the ordinary leaves of the plant, and evidently analogous to the three fleshy confluent bracts which surround the ripe fruit.

In other instances, while the fibrous framework of the leaf retains its usual degree of development, the cellular parenchyma is developed in excess, and, if the increase is so arranged that the number of superposed layers of the cellular tissue is not increased, or their thickness exaggerated, then we get such leaves as those of the "kail," or of the "Savoys" leaves, which are technically called by descriptive botanists "folia bullata." In such leaves the disc of the leaf, rather than the margin, is increased and its surface is thrown up into little conical projections, which are hollow on the under side.

But leaves may increase beyond their usual size without such grave alterations of form as those to which allusion has just been made. It is well known that if a tree be cut down and new shoots be sent out from the stump, the leaves formed on these shoots very often greatly exceed the ordinary ones in dimensions. Such cases as this hardly come under the head of malformations. But where one part only of the leaf is excessively developed, the other portion remaining in its ordinary condition, there can be no hesitation in ranking the phenomenon as teratological.

Thus, Moquin says that the median nerve may be prolonged beyond the blade of the leaf in the form of a short strap or ribbon-like excrescence, while, at other times, the lateral parts of the leaf are subjected to undue development. He refers to a case cited by Schlotterbec[496] in which each side of the leaves of a yellow "violier" (wallflower) was dilated into a kind of projecting lobe on either side of the true apex of the leaf, thus rendering it in appearance three-lobed. M. Delavaud[497] puts on record a case of hypertrophy in the leaves of the common elm, resulting in the formation of an additional lobe and a return to the tricostate type. A leaf so affected is stated to have presented the appearance of a fusion of two leaves. (See also Multiplication of leaves, p. 353.)

The hypertrophied and coloured leaf of Gesnera occupying the place of the absent inflorescence has been previously alluded to under the head of displacement (p. 88).

In some instances hypertrophy is the opposite of suppression; as in the case previously mentioned, where the stipule in the inflorescence of a pea, which is usually undeveloped and rudimentary, was developed in the form of a leafy cup or pitcher.

Another instance of the development of parts usually suppressed, is afforded by the bud-scales of Magnolia fuscata, which may sometimes be found with small but perfect leaves projecting from them, the leaf in this case being the lamina which is ordinarily abortive, while the scales are the representatives of the stipules. This condition is said by Hooker and Thomson ('Flora Indica,' p. 73) to be constant in Magnolia Campbelli.

Enlargement of the perianth, &c.—One or all the segments of the perianth may be subjected to hypertrophy; thus, the utricle of Carex vulpina may frequently be observed to attain four or five times its usual size, the contained ovary remaining unaffected. This condition is generally the result of insect puncture. The growth of parasitic fungi will produce a similar result, as is often seen in the common shepherd's purse, Thlaspi bursa pastoris, and other Cruciferae. The perianth of Rumex aquaticus has been also observed to be occasionally hypertrophied in conjunction with a similar condition of the pistil and with atrophy of the ovules.

Moquin relates having found flowers of Salsola Kali and of Chenopodium murale in which some of the segments of the perianth were five or six times larger than they should be.



The adjoining woodcut represents a singular condition of some cocoa-nuts in the Kew Museum, the appearance of which is due apparently to an hypertrophied condition of the segments of the perianth, which have not only increased in length as the central nut has ripened, but have developed in their tissues that fibrous tissue which ordinarily is found in the pericarp only. This view of the structure of these nuts is borne out by the fact that, under normal circumstances, the base of the perianth contains a considerable amount of fibrous material. In the present case this has increased to such an extent that the fruit appears surrounded by a double husk, by an inner one as usual, and by an outer six-parted one.

It will be remembered that in some of the Cinchonaceae, e.g. Mussaenda, Pinckneya, Calycophyllum, one or more of the calycine lobes are normally dilated and petaloid, the others remaining small and comparatively inconspicuous. Inequality in size is, indeed, a common occurrence in the sepals of many natural orders—Polygalaceae, Leguminosae, Labiatae, &c. The flowers of a rose are mentioned by Moquin as having presented an enlargement of the calyx without any other alterations in form. Schlechtendal has noticed the same thing in Papaver Rhoeas, Reichenbach in Campanula persicifolia, and A. de Candolle in C. Rapunculus. M. Brongniart also has recorded[498] a remarkable variety of Primula sinensis cultivated in the Jardin des Plantes at Paris, wherein the calyx is enormously developed. MM. Fournier and Bonnet have described flowers of Rubus with hypertrophied calyx in conjunction with atrophy and virescence of the petals and other changes.[499]

The corolla may be hypertrophied in some cases, though the change is more rare than in most other organs. Moquin-Tandon mentions as subject to this anomaly species of Galeopsis, Prunella, Scabiosa, and Dipsacus, and also mentions a remarkable variety of Viola odorata cultivated in the neighbourhood of Toulouse. The same learned author also alludes to the so-called double Composites, viz. those in which the usually tubular florets of the disc assume the form and proportions of those of the ray, but these are hardly cases of hypertrophy.

Enlargement of the androecium.—Dunal[500] alludes to a curious instance in a species of Verbascum, the lower flowers of which had hairy stamens as usual, but the filaments of the topmost flower were quite destitute of hairs, and dilated like a flat ribbon.

Moquin relates having found in the neighbourhood of Toulouse a plant of Solanum Dulcamara in which all the upper flowers had two or three stamens of larger dimensions than the others. This happens habitually in Solanum tridynamum and S. Amazonicum, and to a less extent in S. vespertilio and S. cornutum; also in some species of Hyoscyamus. These cases show the close affinity between the Solanaceae and the Scrophulariaceae.

Enlargement of the gynoecium.—In some flowers which have become accidentally female the pistil becomes unusually large, and even to such an extent as to prevent the passage of the pollen. Moquin remarks having seen this enlargement in the pistils of Suaeda fruticosa and Kochia scoparia. The flowers of these Chenopods, under these circumstances, resemble the female flowers of some nettles. The styles of Anemone are also much enlarged as the result of cultivation, and from their petaloid appearance resemble those of the Iris (Goethe). MM. Seringe and Heyland[501] have figured some anomalous flowers of Diplotaxis tenuifolia in which the pistil, more or less distended and deformed, was considerably elongated below, so that it seemed to be borne upon a long stalk, analogous to that of fruits of Capparids. Dr. Klinsman[502] mentions an instance of a similar kind combined with hypertrophy of the sepals and pistils; indeed, the alteration is not uncommon among Crucifers. Pyrethrum inodorum is very subject to hypertrophy. The styles of its radial florets become elongated without any other alteration; at the same time the small corollas become green, and show a tendency to assume a foliaceous condition. Sometimes the hypertrophy affects also the styles of the central florets, and these also become enlarged to double or treble their usual dimensions.

Linne has remarked that the ovary of Tragopogon sometimes assumes very large dimensions, as also does the pappus. He mentions a double-flowered variety, the ovaries of which become ten or twelve times larger than ordinary. M. Clos[503] records an instance in Rumex scutatus wherein the pistil was hypertrophied or club-shaped, and open at the top, or in other cases funnel-shaped, three-lobed at the summit, each lobe terminated by a style. One of the most frequent causes tending to the hypertrophy of the pistil is attributable to the puncture of insects; thus, when the ovary of Juncus articulatus is thus punctured, it acquires a size two or three times larger than ordinary, becoming at the same time sterile.[504]

Occasionally the enlargement may be due to a fusion or incorporation of other elements; thus, M. Lemaire describes an instance in which the style of Sinningia purpurea was much larger than ordinary, tubular, bearing three small lobes, and altogether bearing much resemblance to the column or "gynosteme" of Orchids. This appearance was due to the cohesion and intimate union of the styles with three abortive stamens.[505]

Enlargement of the fruit.—Most cultivated fruits are in a state of true hypertrophy. Girod de Chantrans, after many trials, succeeded in producing a peculiar variety of pea with pods double the ordinary size.[506] M. Clos[507] mentions a case wherein the carpels of Delphinium dictyocarpum were hypertrophied. The change in size may or may not be attended by a difference in form; thus, in certain Leguminosae, as Medicago lupulina, Melilotus leucantha, the carpels are sometimes hypertrophied and elongated, so as to resemble a claw or hook.[508]

The fruit of the common groundsel (Senecio vulgaris) is in its normal condition two or three times shorter than the involucre, and cylindrical for its whole length, but it frequently happens that the fruits become as long as the involucre itself, and taper from the base upwards, so as to become beaked. Under this head may also be mentioned the fleshy bulbils that are found in the capsules of Crinum, Amaryllis, and Agave. These are true seeds enormously dilated.[509] In these seeds the outer coating becomes very thick and fleshy, and is traversed by spiral vessels.

It is obvious that very important results in a practical point of view may be and have been arrived at by cultivators availing themselves of this tendency of plants to increase in dimensions under certain circumstances. It is needless to do more than refer to the many fruits, vegetables, and cereals, which have thus become enlarged and improved by careful selection and rearing.

Alterations of consistence often accompany changes in size. The change may be one whereby the tissues become unusually hardened, by the excessive formation of secondary woody deposits, or softer and more succulent than ordinary, from the formation of an inordinate amount of loose cellular tissue. Generally speaking, the appearances presented in such cases are not sufficiently striking to demand notice other than as regards their size. One illustration, however, may be cited from its singularity. This was the case of a dahlia, in which the centre of the flower was occupied by a projecting knob as large as a walnut, brown in colour, and very hard in texture. This knob was nothing but the enlarged and indurated extremity of the common receptacle, destitute of the scales and florets which usually spring from it. No insect-puncture could be detected, and no other reason for this peculiarity could be ascertained.

FOOTNOTES:

[488] On the subject of knaurs, the reader is referred to Trecul, 'Ann. Sc. Nat.,' 3 ser., vol. xx, p. 65; Lindley, 'Theory of Horticulture;' Rev. M. J. Berkeley, 'Gardeners' Chronicle,' 1855, p. 756.

[489] Jaeger, 'Flora.' 1860. p. 49, tab. i.

[490] 'Revue Horticole,' 1868, p. 110, figs. 12, 13.

[491] The reader may also refer for further information on the subject of malformed pears to Irmisch. 'Flora,' 1858, p. 38, tab. i; Lindley, 'Theory of Horticulture'; Caspary, 'Bull. Soc. Bot. France,' vol. vi, 1859 (Rev. Bibl.), p. 235; Duhamel, 'Phys. Arbr.,' liv. iii, cap. 3. p. 393, fig. 308; Bonnet, 'Recherch. Us. feuilles,' tab. xxvi, fig. 2; Moquin-Tandon, 'El. Ter. Veg.,' p. 384, &c. Some of the cases recorded are, however, instances of true prolification.

[492] 'Revue Horticole' 1868, p. 310.

[493] The interest of this accident is great, as showing how an habitually superior ovary may become inferior—a change so rare in its occurrence that its existence has been denied, and thus forming a marked contrast with the frequency with which the converse change of an inferior ovary to a superior one, from want of union with the calyx or from imperfect development of the peduncle, may be observed. It is also interesting as showing how the peduncle may become swollen, and at the same time how the woody deposit of the endocarp may, as if by compensation, be deficient. And, again, the malformation is not without significance in regard to the relationship between the drupaceous and the pomaceous subdivisions of Rosaceae. The case would fitly be included under alterations of position, but the sheets relating to that subject were printed off before the publication of M. Carriere's notice.

[494] 'Bull. Soc. Bot. France,' 1860, vol. vii, p. 881.

[495] "Monstr. Veget.," in 'Neue Denkschrift.'

[496] "Sched. de Monst. Plant." in 'Act. Helvet.,' t. ii, pl. ii, f. 14.

[497] 'Bull. Soc. Bot. France,' vol. viii, 1861, p. 144.

[498] 'Ann. Sc. Nat.,' ser. 2, t. i, p. 308, pl. ix c, fig. 1.

[499] 'Bull. Soc. Bot. France,' 1862, t. ix, p. 37.

[500] 'Consid. org. Fleur.,' Montpell., 1829, 25, 26, pl. ii, f. 18 and 19.

[501] 'Bull. Bot.,' t. i, p. 7, tab. 1.

[502] 'Linnaea,' vol. x, p. 604, tab. 5.

[503] 'Mem. Acad. Sc. Toulouse,' 5 ser., vol. iii.

[504] 'Re. nosol. Veget.,' pp. 342.

[505] 'Illustr. Hortic.,' 1868, Misc., p. 62.

[506] 'Ann. Soc. Linn.,' Paris, t. i, p. 139.

[507] 'Mem. Acad. Toulouse,' t. 6, 1862.

[508] 'D. C. Prod.,' ii, pp. 172, 187.

[509] Richard, "Obs. sur les bulbilles des Crinum;" 'Ann. Sc. Nat.,' t. ii, p. 12. pl. i, fig. 1, 2. See also A. Braun, "Memoire sur les graines charnues des Amaryllidees," &c.; 'Ann. Sc. Nat.,' 1860, vol. xiv, p. 1, tab. 1.



CHAPTER II.

ELONGATION.

The class of cases coming under this head are sufficiently indicated by the name. There are many instances of this phenomenon occurring under different conditions, which, though unusual, can hardly be called abnormal, such, for instance, as the great lengthening of roots in their search for water, the excessive elongation that takes place in plants when grown at a distance from the light, in their endeavour to attain to which they become, as gardeners phrase it, "drawn." A similar result is brought about in forests or plantations, where long spars are required, by allowing the trees to grow very close to each other, so as to prevent the lateral extension of the branches. When plants grow in running water their roots, stems, and sometimes their leaves, become excessively elongated, as in Ranunculus fluitans, the flower-stalks of Valisneria spiralis, &c. These are cases of variation rather than of malformation, but are none the less curious, or sometimes perplexing; thus, Lapeyrouse described, in his 'Supplement a la flore des Pyrenees,' p. 27, under the name Potamogeton bifolium, a plant which Mr. Bentham subsequently discovered to be nothing but a flowerless variety of Vicia Faba distorted by its growth in water.[510]

Elongation of the root.—This, as already remarked, is more often a variation than a malformation, and is usually due to the presence of water at a distance necessitating growth at the extremities of the root, or to the presence of some obstacle, such as a stone, to avoid which the root elongates till it has passed the obstruction. Occasionally in Crocus corms some of the fibrils may be met with much lengthened and thickened, and invested with a fleshy sheath. It is not certain, however, that these structures are roots; possibly, nay probably, they may be processes from the stem thrust downwards into the soil, similar to the formations already described in the tulip (p. 85, fig. 39).

Elongation of the inflorescence.—Under this heading it is necessary to consider lengthening of the common rachis in the case of an aggregate inflorescence, and lengthening of the individual flower-stalks, whether they be solitary or portions of a multiple inflorescence. The two phenomena may occur together, but they are quite as often independent one of the other. Thus, among Umbelliferae the umbels are occasionally met with supported on unusually long stalks, while the pedicels of the individual flowers may or not be increased in length; so also with some of the Composites, or the heads of flowers of some Leguminosae, Trifolium repens, &c. &c.

Another illustration of the sort is that recorded by M. Fournier, wherein the usually umbellate inflorescence of Pelargonium was, through the lengthening of the main stalk, transformed into a raceme. Among Composites a similar change may sometimes be met with.

MM. Clos and De Schoenefeld have recorded the existence of a variety of the sweet chestnut (Castanea)in which the female catkins were as long, and bore nearly as many flowers, as the male spikes. This is stated to be of constant occurrence in some localities, and to be accompanied by a diminished size of the fruits. A similar elongation has been observed in the case of the walnut, catkins of which have been seen bearing thirty to thirty-five large nuts.[511]

In the strobile of the hop, Humulus Lupulus, a like elongation may sometimes be met with, generally in association with a more or less leafy condition of some of the scales.

Of a similar character, but complicated with extrusion or eversion of an ordinarily concave axis, is the fig described by Zuccarini,[512] and from the appearances presented by which that author draws the inference that the peculiar appearance of the fig is due to the formation of a large number of small bracts blended together for the greater part of their length, and accompanied by the suppression of the internodes, and consequent shortening of the axis. In the monstrous fruit the axis is prolonged, and forms a kind of raceme or catkin, surrounded at the base by numerous bracts, as in many Amentaceae. (See p. 204, figs. 105, 106.)

A lengthening of the axis of the female strobiles of Coniferae is not of infrequent occurrence in Cryptomeria japonica, Larie europaea, &c., and this is usually associated, as has been before stated, with a leaf-like condition of the bracts, and sometimes even with the development of leaf-bearing shoots in place of the scales. (See under Prolification of Inflorescence and Phyllomorphy, and for references, p. 115.)

Elongation of the secondary flower-stalks.—In the previous section the effect of elongation of the main rachis has been considered. A corresponding deviation occurs in the peduncles or pedicels, and sometimes alters the general character of the inflorescence very considerably, converting a spike into a raceme, a raceme into a corymb, a capitulum into an umbel, and so forth. A few such cases may here be alluded to. Fig. 206 represents a specimen of Ranunculus acris, in which the lower and lateral flower-stalks were not only increased in number, but so much lengthened as to form a flat-topped inflorescence—a corymbose cyme. In many leguminous plants, as in Trifolium repens, Lotus corniculatus, &c., what is usually a compact spike, or head of flowers, becomes a raceme from the elongation of the pedicels. In Umbelliferae a similar change occurs, by virtue of which sometimes the umbels themselves, and at other times the florets, are raised on unusually long stalks, as in Angelica Razoulzii, Carum Carui, Thysselinum palustre.[513] In Compositae, when affected by an analogous change, the capitulum assumes the appearance of a simple umbel, as in Hypochaeris radicata, Senecio vulgaris, and other plants.



In some of the double-flowered apples which have been previously alluded to, the flower-stalk is inordinately long when compared with the adjacent ones. Possibly in some of these cases the absence of the usual swelling of the upper part of the peduncle may be connected with its increased length. One of the most striking instances of lengthened flower-stalk occurred in an apple flower, wherein there was no swelling beneath the calyx, while the latter was represented by five perfect stalked leaves.

Elongation of the leaves.—In the case of water plants this change keeps pace with the corresponding growth of the stem, e.g. Ranunculus fluitans, and in terrestrial plants there are varieties termed longifoliar, from the unusual length of the leaves. A similar lengthening occurs in the involucral leaves of Umbelliferae and Compositae, changing very materially the general aspect of the inflorescence. Occasionally, also, the leaf-lobes of parsley (Apium Petroselinum) and other crested-leaved plants may be observed to lose their ordinary wavy form, and to be lengthened into flat riband-like segments, as shown in fig. 207.

The only further illustrations that it is requisite to give of such changes in this place are those occurring in lobed or compounded leaves, which, from a lengthening of the midrib or central stalk, convert a digitate or palmate leaf into a pinnate one. In these instances the lobes or leaflets become separated one from another by a kind of apostasis. This change may be frequently seen in the horse-chestnut, particularly in the young shoots formed after the trees have been pruned or pollarded. In the adjoining cut the intermediate stages between a palmate or digitate leaf to a pinnate one may be seen. The specimens from which the drawing was made were taken from the same tree at the same time.



In the white clover, Trifolium repens, a similar transition may often be observed, as also in some species of Potentilla.[514]

Elongation of the parts of the flower.—The only circumstance that needs especial mention under this section is the great lengthening that sometimes takes place in the carpels, sometimes as a result of injury from insects or fungus, at other times without assignable cause.



In the case of inferior ovaries this lengthening is, perhaps, even more common, as in Umbelliferae, Compositae, &c. The common groundsel (Senecio vulgaris) is especially liable to this form of enlargement of the pistil, either in association with a leafy condition of the pappus or without any such change.

Elongation of the thalamus, placenta, &c.—In some plants, as in Magnolia or Myosurus, the thalamus becomes much elongated, and bears the carpels disposed spirally around it. A similar lengthening occurs in malformed flowers, usually in association with a similar change in the lower or outer part of the flower, by virtue of which the whorls become separated from each other (Apostasis). Elongation and protrusion of the placenta have been already alluded to at p. 119, and also at p. 125. In some of these cases the elongated placenta has taken the form of a leaf-bearing shoot.[515]

Apostasis.—Engelmann made use of this term to express the separation of parts one from another by the unusual elongation of the internodes.[516] He drew a distinction between the separation of individual organs one from the other, and the corresponding displacement of whorls. The subject has already been, to a considerable degree, treated of in these pages under the head of dialysis, displacement, and prolification, and but little need here be added. With reference to the distance between one whorl and another, it will be remembered that, although in the majority of cases the floral whorls are packed closely together, yet in other instances the floral axis becomes elongated, and thus separates the whorls one from another, by structures such as the gynophores, androphores, &c., of Passifloreae, Caryophylleae, Capparideae, &c. &c.

A similar elongation of the thalamus, bringing about the separation of the floral whorls, or of their constituent parts, is very commonly met with in association with median prolification. Where the individual floral elements are thus thrown out of their usual verticillate arrangement, they naturally assume a spiral disposition, and are, in some cases, united by their margins, so that a spiral sheet or tube is formed, surrounding the axis. This frequently occurs in double flowers of the Chinese primrose, Primula sinensis.

Engelmann[517] figures a case wherein the calyx of Anagallis phoenicea was separated by a rather long internode from the corolla, and a like illustration in Torilis Anthriscus.



A frequent change in Crucifers is due to the formation of a long stalk bearing the pod, and thus giving rise to the appearance met as a constant occurrence in Capparids.

In Tropaeolum majus a similar elevation of the pistil may occasionally be seen.

The adjacent figure of a monstrous Delphinium taken from Cramer illustrates well the elongation of the floral axis and the apostasis of the carpels. In this instance the axis is terminated by a second flower (median prolification).

One of the best-marked illustrations of these changes occurs in a permanent malformation of Epilobium hirsutum, specimens of which were originally obtained from the late Professor Henslow. The several floral parts are here, some virescent, others truly foliaceous, and each whorl is separated from its neighbour by a rather long internode. In Fuchsia and Campanula a like change may occasionally be observed.

Engelmann, in addition to those previously mentioned, cites the following plants as having manifested this change:

*Convallaria majalis!, *Tulipa Gesneriana!, Veronica Chamaedrys, Orobanche gracilis, Solanum Lycopersicum, Gentiana campestris, Hypericum, Helleborus fetidus, Caltha palustris, Brassica oleracea! and many Rosaceae, Caryophylleae, Cruciferae, and Ranunculaceae. (See Dialysis, Median Prolification, &c.)

Apostasis of the sub-floral or involucral leaves is not of infrequent occurrence in malformations affecting Compositae and Umbelliferae. In the following genera it has been observed with especial frequency:—Torilis Anthriscus, Eryngium, Athamanta Cervaria, Leontodon, Tragopogon pratense!, Wedelia perfoliata! In garden anemones, also, it is a common deviation.

FOOTNOTES:

[510] 'Cat. Plant.,' Lang., p. 113.

[511] 'Bull. Soc. Bot. France,' t. i, 1854, p. 173, and t. xiii, p. 96.

[512] 'Abhandl. Math. Phys. Class.,' Band. iv, Abhandl. i, tab. i.

[513] See Cramer, 'Bildungsabweich,' pp. 62-79, and Fleischer, 'Missbild, der Culturpflanzen.'

[514] Schlechtendal, 'Bot. Zeit.,' 1844, p. 457; 'Linnaea,' xi, p. 301, xiv, p. 363; 'Bot. Zeit.,' 1856, p. 72; Masters, 'Rep. Brit. Assoc.,' Manchester, 1861; Coultas, 'What may be learnt from a tree,' p. 118.

[515] For further details refer to the chapter on Displacements, p. 86.

[516] 'De Antholysi,' p. 42, Sec. 49.

[517] Loc. cit., tab. 2, f. 6.



CHAPTER III.

ENATION.

Under the above heading are included certain forms arising from excess not of growth, but of development, and consisting in the formation of supplementary lobes or excrescences from various organs.

The new formations are not due either to a repetition or to a partition of any organ, but are out-growths from others previously formed.

In prolification and in multiplication the adventitious structures are of independent origin. In fission the new developments grow simultaneously with the older ones, of which, indeed, they are mere repetitions. Moreover, in fission the supplementary lobes do not, in general, project a plan different from that of the original structure, at least in the first instance, though their direction may ultimately become changed.

In enation the new growth projects from a previously formed organ after it has attained to considerable size, or even after its ordinary proportions have been attained, and it sprouts out from the beginning in a plane which is at a considerable angle to that of the parent organ, and it is sometimes of a different structure from it, and has different functions to fulfil.