Vegetable Teratology Part 58

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 unis.e.xual 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 _Colchic.u.m 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 advent.i.tious 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 bis.e.xual) of--

Ranunculus!

Aconitium!

Delphinium!

Paeonia.

Caryophylleae!

Umbelliferae.

Trifolium repens.

hybridum.

Compositae, sp. pl.

Datura.

Torenia asiatica.

Colchic.u.m 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 dest.i.tute 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 a.s.sociated 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 ill.u.s.trations 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 dest.i.tute 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 ill.u.s.tration 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 ill.u.s.tration 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 alb.u.m_ 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 s.e.xual 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 p.r.o.ne 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 a.s.sumed 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 ill.u.s.tration of the fact that conditions which are abnormal in one plant const.i.tute the natural arrangement in others.

As to the suppressions that occur in the case of the s.e.xual 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 ill.u.s.trations of those intermediate conditions which are also found, under natural circ.u.mstances, between the absolutely unis.e.xual 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.