Vegetable Teratology Part 13

As to the nature of inferior ovaries, see also Payer, 'Bull. Soc. Bot.

Fr.' i, 1854, p. 283. Germain de Saint Pierre, _ibid._, p. 302. Caspary, 'Bull. Soc. Bot. Fr.,' t. vi, 1859, p. 235. Schleiden, 'Principles of Botany,' English translation, p. 368. Duchartre, 'Elements de Botanique,' p. 574. Le Maout et Decaisne, 'Traite general de Botanique,'

p. 57. Bentham, 'Journ. Linn. Soc.,' vol. x, p. 104 (Structure of _Myrtaceae_), and other treatises on Organography.

PART III.

ALTERATIONS OF POSITION.

Necessarily connected with changes in the arrangement of organs are similar alterations in their position; so closely, indeed, that but for convenience sake, it would be unnecessary to treat them separately.

There are, however, some anomalous developments affecting the relative position of organs that could hardly be treated of under any of the preceding paragraphs. There are, also, certain rare instances where an organ is not so much displaced as misplaced; that is to say, it is developed on or from a portion of the plant, which under usual circ.u.mstances does not produce such an organ. In the former instance, the altered position is due to or coexistent with other changes, but in the latter case the new growth may spring from organs otherwise in nowise different from ordinary. The word Displacement is here used to signify the unusual position of an organ; while Heterotaxy may serve to include those cases where a new growth makes its appearance in an unwonted situation, as, for instance, a leaf-bud on a root, &c.

Prolification is also included under this heading, the unusual position of the buds in these cases being of graver import than the mere increase in number. Alterations in the position of the s.e.xual organs are spoken of under the head of Heterogamy.

CHAPTER I.

DISPLACEMENT.

Real or apparent displacement of organs from their usual position is an almost necessary consequence of, or is, at least, coexistent with a large number of teratological phenomena. It is obvious that abnormal unions or disunions, suppressions, hypertrophies, &c., are very liable to bring about or to be accompanied with changes in the position, either of the parts directly affected or of adjoining organs.

In this place, then, it is merely necessary to allude to some of the more important displacements, and to refer for further details to the sections relating to those irregularities of growth on which the displacement depends.

=Displacement of bulbs.=--I owe to the kindness of Mr. James Salter a tulip bulb which had been dug up after flowering, and from the base of which were suspended several small bulbs; and I have since seen another specimen showing the same unusual arrangement. The explanation of these formations seems to be that they correspond to the bulbils ordinarily found in the axils of the scales of the parent organ, and which, in some way or another, have been displaced and thrust into the ground.

Professor de Vriese figures something of the same kind in _Ixia carminosa_.[90]

Of somewhat different nature to those above described was an anomaly described by M. Gay at a meeting of the Botanical Society of France, April 8th, 1859. The plant affected was _Leucoium aestivum_, and the changes observed were apparently attributable to a simple separation of two leaves that are usually contiguous. "Suppose," says M. Gay in describing this malformation, "the first leaf of the terminal bud separated by a long internode from the other leaves, which remain closely packed; and further, suppose an evident thickening of the upper portion of the lengthened internode, and there will be not only a single bulb, bearing with the leaves of the present year all the remnants of the leaves of the two preceding years, but two bulbs placed one above another, on the same axis, separated by the length of the internode."

[Ill.u.s.tration: FIG. 39.--Unusual position of bulbs of tulip; the parent-bulb cut open.]

The formation of bulbs in the axils of the leaves, as happens occasionally in tulips, is further alluded to under the head of hypertrophy.

=Displacements affecting the inflorescence.=--These are, for the most part, dependent on hypertrophy, elongation, atrophy, spiral torsion, &c., but there are a few instances of a different nature, which may here be alluded to as not being coincident with any of the phenomena just mentioned. Sometimes these deviations from the ordinary position have the more interest as affecting characters used to distinguish genera; thus one of the distinctions between rye-gra.s.s (_Lolium_) and wheat (_Tritic.u.m_) resides in the relative position of the spikelets and the main stem; in _Tritic.u.m_ the spikelets are placed with their backs against the rachis, in _Lolium_ with one edge against it; but in a specimen of rye-gra.s.s that has come under my own observation, the arrangement was that of _Tritic.u.m_.

M. Kirschleger relates having found a specimen of _Leucanthemum pratense_, in which the ligulate female flowers were growing singly in the axils of the upper leaves of the stem.[91] The ordinary capitulum would here seem to have been replaced by a spike or a raceme. A less degree of this change wherein a few flowers may be found, as it were, detached from the ordinary capitulum may often be observed in _Compositae_, _Dipsacaceae_, &c. I have also met with specimens of _Lamium alb.u.m_ in which some of the fascicles or cl.u.s.ters of flowers in place of being placed at the same level on opposite sides of the stem were placed alternately one above another.

Caspary[92] mentions a flower of _Aldrovanda vesiculosa_, which was elevated on a stalk that was adherent to the stem for a certain distance, and then separated from it. This flower, with the leaf to which it was axillary, evidently belonged to the whorl beneath, where there was a corresponding deficiency. Another flower of the same plant bore on its pedicel a small leaf, which was doubtless the bract raised above its ordinary position.

M. Fournier mentions an instance in _Pelargonium grandiflorum_, where, owing to the lengthening of the axis, the pedicels, instead of being umbellate, had become racemose; and I owe to the kindness of Dr. Sankey a somewhat similar specimen, but in a less perfect condition. Here there was but a single flower, and that rudimentary, placed at the extremity of the axis. There were several bracts beneath this flower disposed spirally in the 1/3 arrangement, all being empty, excepting the terminal one. In like manner, a head of flowers becomes sometimes converted into an umbel.

=Displacement of leaves.=--A cohesion of parts will sometimes give rise to an apparent displacement, but the true nature of the malformation can, in general, be readily made out.

Steinheil[93] found a specimen of _Salvia Verbenaca_, the leaves of which presented very curious examples of displacement arising from cohesion. Two of these leaves placed at the base of a branch were completely fused in their lower thirds, and divided into two distinct lobes at the upper part; each of these lobes seemed to be as large as the limb of an ordinary leaf. Above these was another very broad one, apparently entire, but evidently produced by a complete cohesion of two.

This completely fused leaf alternated in position with the imperfectly fused one below it; the alternation is explained by supposing that the opposite leaves of each pair were directed one towards the other, and became fused, and that thus resulted the displacement. The dislocation of the organs took place in one direction for one pair of leaves, and in another direction for the other pair, hence the alternation. Thus, leaves normally opposite and decussate may, by fusion, become alternate.

A similar instance occurred to the writer in _Lysimachia vulgaris_, wherein the changes arising from fusion and suppression of parts, &c., were very considerable; as far as the leaves were concerned they presented the following arrangement in succession from below upwards:--first verticillate, then opposite, then spirally alternate, lastly opposite.[94] The term "diremption" has sometimes been applied to cases where leaves are thus apparently dragged out of position.

In _Tradescantia virginica_ I have met with opposite connate leaves; the altered position, however, being due to the union of two stems.

[Ill.u.s.tration: FIG. 40.--Large-coloured leaf occupying the position of the inflorescence in _Gesnera_, after Morren.]

[Ill.u.s.tration: FIG. 41.--Ordinary arrangement of leaves in fascicles of three in _Pinus pinea_ and unusual arrangement of leaves of same plant in spires.]

Twisting of the stem is a frequent cause of the displacement of leaves (see spiral torsion), as also hypertrophy, whether that excess of development take place laterally or lengthwise (see elongation). Atrophy or suppression will also frequently bring about an alteration in the position of leaves; sometimes in such a manner that the place of the suppressed organ is occupied by another one. One of the most curious instances of displacement of leaves arising from suppression is that mentioned by Morren,[95] where, in _Gesnera Geroltiana_, a large leaf apparently occupied the extremity of the axis, a position which, under ordinary circ.u.mstances, no leaf could a.s.sume. The explanation given by the Belgian professor is, that the axis in this case, instead of throwing off a pair of leaves, one on each side, had from some cause or another produced only one; this one not only being much larger than ordinary, but brightly coloured, thus a.s.suming some of the characteristics as well as the position of the inflorescence.

Alterations in the usual arrangement of leaves, however, are not always dependent on or coexistent with other teratological changes, but may simply depend on a natural elongation of the internodes, or on fission or multiplication; for instance, in some conifers, such as the Larch, (_Abies Larix_) or _Pinus pinea_, there may be found at different stages in the growth of the branches leaves in crowded fascicles or tufts; while, when growth is more rapid, the leaves may be disposed in a spiral or alternate manner.

In the yew (_Taxus_) the leaves at the ends of the shoots not unfrequently lose their usual distichous arrangement and become arranged in a close spiral manner, the elongation of the shoot being arrested.

This appears to be the result of the injury effected by some insect.

[Ill.u.s.tration: FIG. 42.--Altered arrangement of leaves of yew, _Taxus baccata_.]

So, too, the alteration from verticillate to spiral, or _vice versa_, may take place without any other notable change.[96] This may frequently be seen in Rhododendrons.

=Displacement of the parts of the flower.=--This subject is partly touched on in the chapters on solution, adhesion, and in those on hypertrophy, elongation, prolification, &c., so that in this place it is only requisite to offer a few general remarks, and to refer to other sections for further details. Morren, in referring to displacement of the floral organs, mentions an instance in a _Fuchsia_, wherein the four petals in place of being alternate with the sepals were placed in front of them, owing to the adhesion that had taken place between the petals and the stamens. He speaks of this transposition as metaphery.[97] The same author also gives an account of the displacement of several of the organs of the flower in _Cypripedium insigne_, the displacement being consequent, apparently, on a spiral torsion proceeding from right to left, and involving the complete or partial suppression of several of the organs of the flower. The dislocation of organs in a spiral direction led Morren to apply the term "speiranthie" to similar deviations from the usual construction. Changes of this kind among _Orchidaceae_ are by no means uncommon; the following may be cited by way of ill.u.s.tration. In a specimen of _Oncidium cucullatum_ furnished me by Mr. Anderson, well known for his success as a cultivator of these plants, there was, a.s.sociated with a cohesion of one sepal with another, and probably dependent on the same cause, a displacement of the sepals and petals--so that all were dragged out of place. This dislocation may be better appreciated by the accompanying formula than even by the woodcut. Let the usual arrangement be thus represented:

S

P ST P

L

S S

S standing for sepal, P for petal, L for lip, ST for stamen; then the dislocated form may be represented thus:

S

P P

T S

S_S L

[Ill.u.s.tration: FIG. 43.--Flower of _Oncidium cucullatum_, showing union of two lower sepals, displacement of column and lip, &c.]

In a specimen of _Cypripedium_ also furnished by Mr. Anderson the appearance was as represented in the accompanying figure and diagrams, figs. 44, 45. Referring to the plan of the natural arrangement at fig.

46, it will be seen that an explanation of the peculiar appearance of the flower may be arrived at by supposing a disunion and lateral displacement of the upper segment of the outer perianth together with the complete absence of the lower one. In the second or inner whorl of the perianth the lip is merely a little oblique on one side, but the lateral petals are distorted, displaced, and adherent one to the other and to the column, while the posterior shield-like rudimentary anther is completely wanting.

[Ill.u.s.tration: FIG. 44.--Malformed flower of _Cypripedium_.]

[Ill.u.s.tration: FIG. 45.--Diagram of malformed _Cypripedium_. _o_, outer segments; _i_, inner segments of perianth; _e_, lip; _s_, stigma; _a_, anther.]

[Ill.u.s.tration: FIG. 46--- Diagram showing ordinary arrangement in _Cypripedium_. _o_, outer, _i_, inner segments of perianth; _e_, lip, _a_, anther, _a'_, abortive stamen; _s_, stigma.]

[Ill.u.s.tration: FIG. 47.--Plan of flower of _Lycaste Skinneri_ showing displacement of organs.]