=Increased number of bracts.=--This is not of infrequent occurrence; one of the most curious instances is that recorded by Mr. Edwards[399] in _Cerastium glomeratum_, where, in place of the usual pair of bracts at the base of the head of flowers, there was a whorl of six or eight, forming an involucre. The flowers in this case were apetalous and imperfect.

=Polyphylly of the calyx.=--This may occur without any other perceptible change, while at other times the number of the other parts of the flower is proportionately increased. In a flower of a plum six sepals in place of five sometimes exist; a precisely similar occurrence in the flowers of the elder (_Sambucus_), the _Fuchsia_, and of _OEnanthe crocata_, may occasionally be met with. In the latter case, indeed, there are sometimes as many as ten segments to the calyx, and this without the other parts of the flower being correspondingly augmented. Among monocotyledons a similar increase is not uncommon, as in _Tulipa_, _Allium_, _Iris_, _Narcissus_, &c.

In some plants there seems to exist normally much variation in the number of parts; thus in some species of _Lacistema_ in adjacent flowers the calyx may be found with four, five, or six segments.

Most of these cases of polyphylly affecting the calyx may be explained by lateral chorisis or fission.

=Polyphylly of the corolla.=--This may happen in connection with similar alterations in the calyx and stamens, or sometimes as an isolated occurrence. In the latter case it may be due to lateral chorisis, to subst.i.tution, or to the development of organs usually suppressed; thus, when in aconites we meet with four or five horn-like nectaries (petals) instead of two only, as usual, the supernumerary ones are accounted for by the inordinate development of parts which ordinarily are in an abortive or rudimentary state only. This is borne out by what happens in _Balsamineae_. In the common garden balsam the fifth petal is occasionally present, while in _Hydrocera triflora_ this petal is always present.

In a flower of a _Cyclamen_ recently examined there were ten petals in one series, the additional five being evidently due to the subdivision of the five primary ones; the natural circular plan of the flower was here replaced by an elliptical one. A similar occurrence takes place in the flowers of maples (_Acer_), which sometimes show an increased number of parts in their floral whorls and an elliptical outline. Whether the additional organs in this last case are the result of complete lateral chorisis or of multiplication proper I do not know.

Orchids are very subject to an increase in the number of their labella.

As ill.u.s.trations may be cited an instance recorded by Mr. J. T.

Moggridge in a flower of _Ophrys insectifera_, and in which there were two labella without any other visible deviation from the ordinary conformation.[400]

I am indebted to Mr. Hemsley for the communication of a similar specimen in _O. apifera_, in which there were two divergent lips, each with the same peculiar markings. One of the sepals in this flower was adherent to one of the lateral petals. This augmentation of the labella depends sometimes on the separation, one from the other, of the elements of which the lip is composed, at other times on the development, in the guise of lips, of stamens which are usually suppressed (see p. 380).

The following enumeration will suffice to show the genera in which an increased number of petals or perianth-segments in any given whorl most frequently occurs.

Anemone!

Ranunculus!

Aconitum!

Rapha.n.u.s.

Bunias.

Saponaria.

Dianthus!

Pelargonium!

Hibiscus.

Fuchsia.

Sarothamnus!

Lotus!

Ulex!

Prunus!

Trifolium.

OEnanthe and Umbellif. pl.!

Sambucus!

Bryonia.

Campanula.

Solanum.

Veronica.

Cyclamen!

Primula!

Anagallis!

Plumbago.

Jasminum.

Syringa!

Tradescantia.

Iris.

Tigridia.

Narcissus.

Tulipa.

Convallaria!

Paris!

Hyacinthus!

Allium!

Ornithogalum.

Orchideae, sp. pl.!

For other ill.u.s.trations see multiplication of whorls, petalody; see also Moquin, loc. cit., p. 350. Engelmann, loc. cit., p.

20, -- 18. Cramer, loc. cit., p. 25.

=Polyphylly of the androecium.=--An increased number of stamens frequently accompanies the corresponding alterations in other whorls, and seems, if anything, to be more frequent among monocotyledonous plants than among dicotyledonous ones; thus, we occasionally find tetramerous flowers in _Crocus_, _Hyacinthus_, _Tulipa_, _Iris_, _Tigridia_, &c., and more rarely in _Yucca_ (_Y. flexilis_[401]).

The increased number of stamens in a single whorl may result from a development of organs usually suppressed, and const.i.tute a form of regular peloria as in _Linaria_, wherein a fifth stamen is occasionally met with. Among normally didynamous plants such numerical rest.i.tution, so to speak, is not unusual; thus, in _Veronica_ four and five stamens occur. Fresenius has seen five stamens in _Lamium_, _Mentha_, _Chelone_;[402] Bentham in _Melittis_, and other instances are cited under the head of peloria. Chorisis may also serve to account for some of these cases; thus, Eichler[403] figures a flower of _Matthiola annua_ with five long stamens instead of four; one of the long pairs of stamens has here undergone a greater degree of repet.i.tion than usual. De Candolle[404] cites and figures a curious form of _Capsella Bursa-pastoris_ sent him by Jacquin, and which was to some extent reproduced by seed. In the flowers of this variety there were no petals, but ten stamens; hence De Candolle inferred that the petals were here replaced by stamens, but Moquin[405] objects, and with justice, to this view, as the ten stamens are all on the same line; he considers the additional stamens to be the result of chorisis. Buchenau[406] mentions the presence of seven stamens in another Crucifer, _Ionopsidium acaule_. Here the supernumerary organ was placed between two of the long stamens. The effect of chorisis in producing an augmentation of parts is well seen in some plants that have some of their flowers provided with staminodes or abortive stamens, and others with cl.u.s.ters or phalanges of perfect stamens. Thus, in the female flowers of _Liquidambar_ there are five small staminodes without anthers, whereas in the male flower the stamens are numerous and grouped together in phalanges, so that the relation of simple to compound stamens is in this case readily seen, as also in many _Malvaceae_, _Sterculiaceae_, _Byttneriaceae_, _Tiliaceae_, and _Myrtaceae_. It is probably the idea of splitting or dilamination involved in the word chorisis that has led many English botanists to hesitate about accepting the notion. Had they looked upon the process as identical with that by which a branched inflorescence replaces an unbranched one, or a compound leaf takes the place of a simple one, the objections would not have been raised with such force. The process consists, in most cases, not so much in actual cleavage of a pre-existing organ as in the development of new-growing points from the old ones.

An ill.u.s.tration given by Moquin from Dunal[407] goes far to support the notion here adopted. The majority of the stamens of laurels (_Laurus_) have, says M. Dunal, on each side of the base of their filaments a small glandular bifid appendage; these excrescences are liable to be changed into small stamens. The male flowers have a four-leaved calyx, and sometimes eight stamens, each with two glands, four in one row, opposite to the sepals, four in a second series alternating with the first. More generally two of the stamens are dest.i.tute of glands, but have in their place a perfectly developed stamen, so that in these latter flowers there are twelve stamens.

M. Clos[408] mentions a flower of rue (_Ruta_) wherein there were two stamens joined together below and placed in front of a petal, as in _Peganum_.

Buchenau[409] mentions a flower of _Lotus uliginosus_ in which there were eleven stamens, namely, two free and nine monadelphous; and Hildebrand describes an a.n.a.logous increase in a flower of _Sarothamnus scoparius_ in which, in conjunction with a seven-toothed calyx, there were two carinas and fourteen stamens. It would seem probable in this case that there was a coalescence of two flowers at an early date and consequent suppression of some of the parts of the flower. Whether this was the case or not in this particular ill.u.s.tration, it is nevertheless certain that many of the recorded instances of increased number in the organs of a flower are really the results of a fusion of two or more flowers, though frequently in the adult state but few traces of the coalescence are to be seen.

=Polyphylly of the gynoecium.=--Moquin[410] remarks that, as the pistils are, generally speaking, more or less subject to pressure, owing to their central position, and it may be added owing to their later development, than the other parts of the flower, they are more subject to suppression than to multiplication; nevertheless, augmentation in the number of carpels does occasionally take place, especially when the other parts of the flower are also augmented in number. Sometimes this increase in the number of carpels is due to pure multiplication, without any other change. At other times the increase is due to a subst.i.tution of stamens or other organs for carpels (see Subst.i.tutions). In other cases the augmentation seems to be due to the development of parts usually suppressed; for instance, in _Antirrhinum_, where there are usually only two carpels present, but where, under peculiar circ.u.mstances, five may be found--thus rendering the symmetry complete.[411] In _Papilionaceae_, wherein usually only one carpel is developed, we occasionally find two, or even more, as in _Wistaria_, _Gleditschia_, _Trifolium_, &c. In _Prunus_ and _Amygdalus_ from two to five carpels are occasionally to be found,[412] in _Mimosa_ five, in _Umbelliferae_ three to five; in some composites, _e.g._ _Spilanthes_, five carpels have also been noticed; in _Cruciferae_ three and four, in gra.s.ses three.[413] The double cocoa-nut affords an ill.u.s.tration of the development of two carpels out of three, one only generally arriving at perfection. Triple nuts (_Corylus_) also owe their peculiarity to the equal development of all three carpels which exist in the original flower, but of which, under ordinary circ.u.mstances, two become abortive.

It is necessary, however, to distinguish these cases from those in which two embryos are developed in one seed.

The following list may serve to show in what genera this change has been most frequently noticed, and it may be said in general terms that _Cruciferae_, _Umbelliferae_, and _Liliaceae_, are the orders most frequently affected. Cases of peloria are not included in the subjoined list.

Nigella.

Aquilegia.

Paeonia!

Delphinium!

Iberis.

Diplotaxis.

Lunaria.

Ricotiana.

Octadenia.

Draba!

Lepidium.

*Cheiranthus!

Dianthus.

Bra.s.sica!

Parna.s.sia.

*Acer!

Ptelea.

Citrus!

Philadelphus.

Prunus!

Amygdalus!

Crataegus!