Vegetable Teratology Part 60

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 ma.s.s consisted of a similar tissue to the fleshy portion of the fruit, but with far less wrinkled walls, and more indistinct intercellular s.p.a.ces. The most striking point, however, was the immense quant.i.ty of very irregular and unequal starch-grains with which they were gorged, which gave a peculiar sparkling appearance to them when seen _en ma.s.se_. 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, pa.s.sing gradually into the ordinary leaves of the plant, and evidently a.n.a.logous 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.

[Ill.u.s.tration: 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 circ.u.mstances, 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_, _l.a.b.i.atae_, &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 a.s.sume 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 _Verbasc.u.m_, the lower flowers of which had hairy stamens as usual, but the filaments of the topmost flower were quite dest.i.tute 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. Amazonic.u.m_, 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 pa.s.sage 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 circ.u.mstances, 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, a.n.a.logous 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 a.s.sume 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 a.s.sumes 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 circ.u.mstances. 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 ill.u.s.tration, 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 k.n.o.b as large as a walnut, brown in colour, and very hard in texture. This k.n.o.b was nothing but the enlarged and indurated extremity of the common receptacle, dest.i.tute 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] 'Ill.u.s.tr. Hortic.,' 1868, Misc., p. 62.