Vegetable Teratology / An Account of the Principal Deviations from the Usual Construction of Plants

by Maxwell T. Masters

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.

Fig. 200.—Pelargonium, one branch of which was hypertrophied.

Enlargement of axile organs.—All the species of Pelargonium, Geranium, Mirabilis, as well as those of Caryophylleæ 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 Cratægus, &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.

Fig. 201.—Formation of tubers or hypertrophied buds in the axils of leaves in the potato.

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.

Fig. 202.—Inflorescence of ash (Fraxinus), with hypertrophied pedicels, flowers absent.

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]

Fig. 203.—Monstrous pear, showing extension and ramification of the succulent floral axis. The bases of the sepals are also succulent.

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. Carrière[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.

Fig. 204.—Monstrous pear, showing extension and swelling of axis, &c.

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. Carrière[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 placentæ 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 Cruciferæ. 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.

Fig. 205.—Hypertrophy of the perianth in Cocos nucifera.

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 Cinchonaceæ, e.g. Mussænda, 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—Polygalaceæ, Leguminosæ, Labiatæ, &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 Rhœas, 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 andrœcium.—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 Solanaceæ and the Scrophulariaceæ.

Enlargement of the gynœcium.—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 Suæda 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.

Linné 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 Leguminosæ, 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.