§ 4 Modifications of the Type
248. The Deviations, as they may be called, from the assumed type or pattern of flower are most various and extensive. The differences between one species and another of the same genus are comparatively insignificant; those between different genera are more striking; those between different families and classes of plants more and more profound. They represent different adaptations to conditions or modes of life, some of which have obvious or probable utilities, although others are beyond particular explanation. The principal modifications may be conveniently classified. First those which in place of perfect (otherwise called hermaphrodite or bisexual) flowers, give origin to
249. Unisexual, or Separated, or Diclinous Flowers, imperfect flowers, as they have been called in contradistinction to perfect flowers; but that term is too ambiguous. In these some flowers want the stamens, while others want the pistils. Taking hermaphrodite flowers as the pattern, it is natural to say that the missing organs are suppressed. This expression is justified by the very numerous cases in which the missing parts are abortive, that is, are represented by rudiments or vestiges, which serve to exemplify the plan, although useless as to office. Unisexual flowers are Monœcious (or Monoicous, i. e. of one household), when flowers of both sorts or sexes are produced by the same individual plant, as in the Ricinus or Castor-oil Plant, Fig. 230.
Diœcious (or Dioicous, i. e. of separate households), when the two kinds are borne on different plants; as in Willows, Poplars, Hemp, and Moonseed, Fig. 231, 232.
Polygamous, when the flowers are some of them perfect, and some staminate or pistillate only.
250. A blossom having stamens and no pistil is a Staminate or Male flower. Sometimes it is called a Sterile flower, not appropriately, for other flowers may equally be sterile. One having pistil but no stamens is a Pistillate or Female flower.
251. Incomplete Flowers are so named in contradistinction to complete: they want either one or both of the floral envelopes. Those of Fig. 230 are incomplete, having calyx but no corolla. So is the flower of Anemone (Fig. 233), although its calyx is colored like a corolla. The flowers of Saururus or Lizard’s-tail, although perfect, have neither calyx nor corolla (Fig. 234). Incomplete flowers, accordingly, are Naked or Achlamydeous, destitute of both floral envelopes, as in Fig. 234, or Apetalous, when wanting only the corolla. The case of corolla present and calyx wholly wanting is extremely rare, although there are seeming instances. In fact, a single or simple perianth is taken to be a calyx, unless the absence or abortion of a calyx can be made evident.
252. In contradistinction to regular and symmetrical, very many flowers are Irregular, that is, with the members of some or all of the floral circles unequal or dissimilar, and Unsymmetrical, that is, when the circles of the flower or some of them differ in the number of their members. (Symmetrical and unsymmetrical are used in a different sense in some recent books, but the older use should be adhered to). Want of numerical symmetry and irregularity commonly go together; and both are common. Indeed, few flowers are entirely symmetrical beyond calyx, corolla, and perhaps stamens; and probably no irregular blossoms are quite symmetrical.
253. Irregular and Unsymmetrical Flowers may therefore be illustrated together, beginning with cases which are comparatively free from other complications. The blossom of Mustard, and of all the very natural family which it represents (Fig. 235, 236), is regular but unsymmetrical in the stamens. There are four equal sepals, four equal petals; but six stamens, and only two members in the pistil, which for the present may be left out of view. The want of symmetry is in the stamens. These are in two circles, an outer and an inner. The outer circle consists of two stamens only; the inner has its proper number of four. The flower of Violet, which is on the plan of five, is symmetrical in calyx, corolla, and stamens, inasmuch as each of these circles consists of five members; but it is conspicuously irregular in the corolla, one of the petals being very different from the rest.
254. The flowers of Larkspur, and of Monkshood or Aconite, which are nearly related, are both strikingly irregular in calyx and corolla, and considerably unsymmetrical. In Larkspur (Fig. 239-241) the irregular calyx consists of five sepals, one of which, larger than the rest, is prolonged behind into a large sac or spur; but the corolla is of only four petals (of two shapes),—the fifth, needed to complete the symmetry, being left out. And the Monkshood (Fig. 242-244) has five very dissimilar sepals, and a corolla of only two very small and curiously-shaped petals,—the three needed to make up the symmetry being left out. The stamens in both are out of symmetry with the ground-plan, being numerous. So are the pistils, which are usually diminished to three, sometimes to two or to one.
255. Flowers with Multiplication of Parts are very common. The stamens are indefinitely numerous in Larkspur and in Monkshood (Fig. 242, 243), while the pistils are fewer than the ground-plan suggests. Most Cactus-flowers have all the organs much increased in number (Fig. 229), and so of the Water-Lily. In Anemone (Fig. 233) the stamens and pistils are multiplied while the petals are left out. In Buttercups or Crowfoot, while the sepals and petals conform to the ground-plan of five, both stamens and pistils are indefinitely multiplied (Fig. 245).
Coalescence of parts of the same circle by their contiguous margins; and Adnation, or the union of adjacent circles or unlike parts.
257. Coalescence is not rare in leaves, as in the upper pairs of Honeysuckles, Fig. 163. It may all the more be expected in the crowded circles or whorls of flower-leaves. Datura or Stramonium (Fig. 246) shows this coalescence both in calyx and corolla, the five sepals and the five petals being thus united to near their tips, each into a tube or long and narrow cup. These unions make needful the following terms:—
Gamopetalous, said of a corolla the petals of which are thus coalescent into one body, whether only at base or higher. The union may extend to the very summit, as in Morning Glory and the like (Fig. 247), so that the number of petals in it may not be apparent. The old name for this was Monopetalous, but that means “one-petalled;” while gamopetalous means “petals united,” and therefore is the proper term.
Polypetalous is the counterpart term, to denote a corolla of distinct, that is, separate petals. As it means “many petalled,” it is not the best possible name, but it is the old one and in almost universal use.
Gamosepalous applies to the calyx when the sepals are in this way united.
Polysepalous, to the calyx when of separate sepals or calyx-leaves.
258. Degree of union or of separation in descriptive botany is expressed in the same way as is the lobing of leaves (139). See Fig. 249-253, and the explanations.
259. A corolla when gamopetalous commonly shows a distinction (well marked in Fig. 249-251) between a contracted tubular portion below, the Tube, and the spreading part above, the Border or Limb. The junction between tube and limb, or a more or less enlarged upper portion of the tube between the two, is the Throat. The same is true of the calyx.
260. Some names are given to particular forms of the gamopetalous corolla, applicable also to a gamosepalous calyx, such as
Wheel-shaped, or Rotate; when spreading out at once, without a tube or with a very short one, something in the shape of a wheel or of its diverging spokes, Fig. 252, 253.
Salver-shaped, or Salver-form; when a flat-spreading border is raised on a narrow tube, from which it diverges at right angles, like the salver represented in old pictures, with a slender handle beneath, Fig. 249-251, 255.
Bell-shaped, or Campanulate; where a short and broad tube widens upward, in the shape of a bell, as in Fig. 254.
Funnel-shaped, or Funnelform; gradually spreading at the summit of a tube which is narrow below, in the shape of a funnel or tunnel, as in the corolla of the common Morning Glory (Fig. 247) and of the Stramonium (Fig. 246).
Tubular; when prolonged into a tube, with little or no spreading at the border, as in the corolla of the Trumpet Honeysuckle, the calyx of Stramonium (Fig. 246), etc.
261. Although sepals and petals are usually all blade or lamina (123), like a sessile leaf, yet they may have a contracted and stalk-like base, answering to petiole. This is called its Claw, in Latin Unguis. Unguiculate petals are universal and strongly marked in the Pink tribe, as in Soapwort (Fig. 248).
262. Such petals, and various others, may have an outgrowth of the inner face into an appendage or fringe, as in Soapwort, and in Silene (Fig. 259), where it is at the junction of claw and blade. This is called a Crown, or Corona. In Passion-flowers (Fig. 260) the crown consists of numerous threads on the base of each petal.
263. Irregular Flowers may be polypetalous, or nearly so, as in the papilionaceous corolla; but most of them are irregular through coalescence, which often much disguises the numerical symmetry also. As affecting the corolla the following forms have received particular names:
264. Papilionaceous Corolla, Fig. 261, 262. This is polypetalous, except that two of the petals cohere, usually but slightly. It belongs only to the Leguminous or Pulse family. The name means butterfly-like; but the likeness is hardly obvious. The names of the five petals of the papilionaceous corolla are curiously incongruous. They are,
The Standard or Banner (Vexillum), the large upper petal which is external in the bud and wrapped around the others.
The Wings (Alæ), the pair of side petals, of quite different shape from the standard.
The Keel (Carina), the two lower and usually smallest petals; these are lightly coalescent into a body which bears some likeness, not to the keel, but to the prow of a boat; and this encloses the stamens and pistil. A Pea-blossom is a typical example; the present illustration is from a species of Locust, Robinia hispida.
265. Labiate Corolla (Fig. 256-258), which would more properly have been called Bilabiate, that is, two-lipped. This is a common form of gamopetalous corolla; and the calyx is often bilabiate also. These flowers are all on the plan of five; and the irregularity in the corolla is owing to unequal union of the petals as well as to diversity of form. The two petals of the upper or posterior side of the flower unite with each other higher up than with the lateral petals (in Fig. 256, quite to the top), forming the Upper lip: the lateral and the lower similarly unite to form the Lower lip. The single notch which is generally found at the summit of the upper lip, and the two notches of the lower lip, or in other words the two lobes of the upper and the three of the lower lip, reveal the real composition. So also does the alternation of these five parts with those of the calyx outside. When the calyx is also bilabiate, as in the Sage, this alternation gives three lobes or sepals to the upper and two to the lower lip. Two forms of the labiate corolla have been designated, viz.:—
Ringent or Gaping, when the orifice is wide open, as in Fig. 256.
Personate or Masked, when a protuberance or intrusion of the base of the lower lip (called a Palate) projects over or closes the orifice, as in Snapdragon and Toad-Flax, Fig. 257, 258.
266. There are all gradations between labiate and regular corollas. In those of Gerardia, of some species of Pentstemon, and of Catalpa (Fig. 263-265), the labiate character is slight, but is manifest on close inspection. In almost all such flowers the plan of five, which is obvious or ascertainable in the calyx and corolla, is obscured in the stamens by the abortion or suppression of one or three of their number.
267. Ligulate Corolla. The ligulate or Strap-shaped corolla mainly belongs to the family of Compositæ, in which numerous small flowers are gathered into a head, within an involucre that imitates a calyx. It is best exemplified in the Dandelion and in Chiccory (Fig. 266). Each one of these straps or Ligules, looking like so many petals, is the corolla of a distinct flower: the base is a short tube, which opens out into the ligule: the five minute teeth at the end indicate the number of constituent petals. So this is a kind of gamopetalous corolla, which is open along one side nearly to the base, and outspread. The nature of such a corolla (and of the stamens also, to be explained in the next section) is illustrated by the flower of a Lobelia, Fig. 285.
268. In Asters, Daisies, Sunflower, Coreopsis (Fig. 268), and the like, only the marginal (or Ray) corollas are ligulate; the rest (those of the Disk) are regularly gamopetalous, tubular, and five-lobed at summit; but they are small and individually inconspicuous, only the ray-flowers making a show. In fact, those of Coreopsis and of Sunflower are simply for show, these ray-flowers being not only sterile, but neutral, that is, having neither stamens nor pistil. But in Asters, Daisies, Golden-rods, and the like, these ray-flowers are pistillate and fertile, serving therefore for seed-bearing as well as for show. Let it not be supposed that the show is useless. See Section XIII.
269. Adnation, or Consolidation, is the union of the members of parts belonging to different circles of the flower (256). It is of course understood that in this (as likewise in coalescence) the parts are not formed and then conjoined, but are produced in union. They are born united, as the term adnate implies. To illustrate this kind of union, take the accompanying series of flowers (Fig. 270-274), shown in vertical section. In the first, Fig. 270, Flax-flower, there is no adnation; sepals, petals, and stamens, are free as well as distinct, being separately borne on the receptacle, one circle within or above the next; only the five pistils have their ovaries coalescent. In Fig. 271, a Cherry-flower, the petals and stamens are borne on the throat of the calyx-tube; that is, the sepals are coalescent into a cup, and the petals and stamens are adnate to the inner face of this; in other words, the sepals, petals, and stamens are all consolidated up to a certain height. In Fig. 272, a Purslane-flower, the same parts are adnate to or consolidated with the ovary up to its middle. In Fig. 273, a Hawthorn-flower, the consolidation has extended over the whole ovary; and petals and stamens are adnate to the calyx still further. In Fig. 274, a Cranberry-blossom, it is the same except that all the parts are free at the same height; all seem to arise from the top of the ovary.
270. In botanical description, to express tersely such differences in the relation of these organs to the pistil, they are said to be
Hypogynous (i. e. under the pistil) when they are all free, that is, not adnate to pistil nor connate with each other, as in Fig. 270.
Perigynous (around the pistil) when connate with each other, that is, when petals and stamens are inserted or borne on the calyx, whether as in Cherry-flowers (Fig. 271) they are free from the pistil, or as in Purslane and Hawthorn (Fig. 272, 273) they are also adnate below to the ovary.
Epigynous (on the ovary) when so adnate that all these parts appear to arise from the very summit of the ovary, as in Fig. 274. The last two terms are not very definitely distinguished.
271. Another and a simpler form of expression is to describe parts of the flower as being
Free, when not united with or inserted upon other parts.
Distinct, when parts of the same kind are not united. This term is the counterpart of coalescent, as free is the counterpart of adnate. Many writers use the term “free” indiscriminately for both; but it is better to distinguish them.
Connate is a term common for either not free or not distinct, that is, for parts united congenitally, whether of same or of different kinds.
Adnate, as properly used, relates to the union of dissimilar parts.
272. In still another form of expression, the terms superior and inferior have been much used in the sense of above and below.
Superior is said of the ovary of Flax-flower, Cherry, etc., because above the other parts; it is equivalent to “ovary free.” Or it is said of the calyx, etc., when above the ovary, as in Fig. 273-275.
Inferior, when applied to the ovary, means the same as “calyx adnate;” when applied to the floral envelopes, it means that they are free.
273. Position of Flower or of its Parts. The terms superior and inferior, or upper and lower, are also used to indicate the relative position of the parts of a flower in reference to the axis of inflorescence. An axillary flower stands between the bract or leaf which subtends it and the axis or stem which bears this bract or leaf. This is represented in sectional diagrams (as in Fig. 275, 276) by a transverse line for the bract, and a small circle for the axis of inflorescence. Now the side of the blossom which faces the bract is the Anterior, or Inferior, or Lower side; while the side next the axis is the Posterior, or Superior, or Upper side of the flower.
274. So, in the labiate corolla (Fig. 256-258), the lip which is composed of three of the five petals is the anterior, or inferior, or lower lip; the other is the posterior, or superior, or upper lip.
275. In Violets (Fig. 238, 276), the odd sepal is posterior (next the axis); the odd petal is therefore anterior, or next the subtending leaf. In the papilionaceous flower (Fig. 261, and diagram, Fig. 275), the odd sepal is anterior, and so two sepals are posterior; consequently, by the alternation, the odd petal (the standard) is posterior or upper, and the two petals forming the keel are anterior or lower.
Notes
256 Flowers modified by Union of Parts, so that these parts more or less lose the appearance of separate leaves or other organs growing out of the end of the stem or receptacle, are extremely common. There are two kinds of such union, namely:—