Part 9

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 (_Alae_), 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 Compositae, 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.

Sec. 5. ARRANGEMENT OF PARTS IN THE BUD.

276. =AEstivation= was the fanciful name given by Linnaeus to denote the disposition of the parts, especially the leaves of the flower, before _Anthesis_, i. e. before the blossom opens. _Praefloration_, a better term, is sometimes used. This is of importance in distinguishing different families or genera of plants, being generally uniform in each. The aestivation is best seen by making a slice across the flower-bud; and it may be expressed in diagrams, as in the accompanying figures.

277. The pieces of the calyx or the corolla either overlap each other in the bud, or they do not. When they do not overlap, the aestivation is

_Valvate_, when the pieces meet each other by their abrupt edges, without any infolding or overlapping; as the calyx of the Linden or Basswood (Fig. 277).

_Induplicate_, which is valvate with the margins of each piece projecting inwards, as in the calyx of a common Virgin's-bower, Fig. 278, or

_Involute_, which is the same but the margins rolled inward, as in most of the large-flowered species of Clematis, Fig. 279.

_Reduplicate_, a rarer modification of valvate, is similar but with margins projecting outward.

_Open_, the parts not touching in the bud, as the calyx of Mignonette.

278. When the pieces overlap in the bud, it is in one of two ways; either every piece has one edge in and one edge out, or some pieces are wholly outside and others wholly inside. In the first case the aestivation is

_Convolute_, also named _Contorted_ or _Twisted_, as in Fig. 280, a cross-section of a corolla very strongly thus convolute or rolled up together, and in the corolla of a Flax-flower (Fig. 281), where the petals only moderately overlap in this way. Here one edge of every petal covers the next before it, while its other edge is covered by the next behind it. The other mode is the

_Imbricate_ or _Imbricated_, in which the outer parts cover or overlap the inner so as to "break joints," like tiles or shingles on a roof; whence the name. When the parts are three, the first or outermost is wholly external, the third wholly internal, the second has one margin covered by the first while the other overlaps the third or innermost piece: this is the arrangement of alternate three-ranked leaves (187). When there are five pieces, as in the corolla of Fig. 225, and calyx of Fig. 281, as also of Fig. 241, 276, two are external, two are internal, and one (the third in the spiral) has one edge covered by the outermost, while its other edge covers the innermost; which is just the five-ranked arrangement of alternate leaves (188). When the pieces are four, two are outer and two are inner; which answers to the arrangement of opposite leaves.

279. The imbricate and the convolute modes sometimes vary one into the other, especially in the corolla.

280. In a gamopetalous corolla or gamosepalous calyx, the shape of the tube in the bud may sometimes be noticeable. It may be

_Plicate_ or _Plaited_, that is, folded lengthwise; and the plaits may either be turned outwards, forming projecting ridges, as in the corolla of Campanula; or turned inwards, as in that of Gentian Belladonna; or

_Supervolute_, when the plaits are convolutely wrapped round each other, as in the corolla of Morning Glory and of Stramonium, Fig. 282.

Section IX. STAMENS IN PARTICULAR.

281. =Androecium= is a technical name for the staminate system of a flower (that is, for the stamens taken together), which it is sometimes convenient to use. The preceding section has dealt with modifications of the flower pertaining mainly to calyx and corolla. Those relating to the stamens are now to be indicated. First as to

282. Insertion, or place of attachment. The stamens usually go with the petals. Not rarely they are at base

_Epipetalous_, that is, inserted on (or adnate to) the corolla, as in Fig. 283. When free from the corolla, they may be

_Hypogynous_, inserted on the receptacle under the pistil or gynoecium.

_Perigynous_, inserted on the calyx, that is, with the lower part of filament adnate to the calyx-tube.

_Epigynous_, borne apparently on the top of the ovary; all which is explained in Fig. 270-274.

_Gynandrous_ is another term relating to insertion of rarer occurrence, that is, where the stamens are inserted on (in other words, adnate to) the style, as in Lady's Slipper (Fig. 284), and in the Orchis family generally.

283. =In Relation to each Other=, stamens are more commonly

_Distinct_, that is, without any union with each other. But when united, the following technical terms of long use indicate their modes of mutual connection:--

_Monadelphous_ (from two Greek words, meaning "in one brotherhood"), when united by their filaments into one set, usually into a ring or cup below, or into a tube, as in the Mallow Family (Fig. 286), the Passion-flower (Fig. 260), the Lupine (Fig. 287), and in Lobelia (Fig. 285).

_Diadelphous_ (meaning in two brotherhoods), when united by the filaments into two sets, as in the Pea and most of its near relatives (Fig. 288), usually nine in one set, and one in the other.

_Triadelphous_ (three brotherhoods), when the filaments are united in three sets or clusters, as in most species of Hypericum.

_Pentadelphous_ (five brotherhoods), when in five sets, as in some species of Hypericum and in American Linden (Fig. 277, 289).

_Polyadelphous_ (many or several brotherhoods) is the term generally employed when these sets are several, or even more than two, and the particular number is left unspecified. These terms all relate to the filaments.

_Syngenesious_ is the term to denote that stamens have their anthers united, coalescent into a ring or tube; as in Lobelia (Fig. 285), in Violets, and in all of the great family of Compositae.

284. =Their Number= in a flower is commonly expressed directly, but sometimes adjectively, by a series of terms which were the name of classes in the Linnaean artificial system, of which the following names, as also the preceding, are a survival:--

_Monandrous_, i. e. solitary-stamened, when the flower has only one stamen,

_Diandrous_, when it has two stamens only,

_Triandrous_, when it has three stamens,

_Tetrandrous_, when it has four stamens,

_Pentandrous_, when it has five stamens,

_Hexandrous_, when with six stamens, and so on to

_Polyandrous_, when it has many stamens, or more than a dozen.

285. For which terms, see the Glossary. They are all Greek numerals prefixed to _-andria_ (from the Greek), which Linnaeus used for _androecium_, and are made into an English adjective, _-androus_. Two other terms, of same origin, designate particular cases of number (four or six) in connection with unequal length. Namely, the stamens are

_Didynamous_, when, being only four, they form two pairs, one pair longer than the other, as in the Trumpet Creeper, in Gerardia (Fig. 263), etc.

_Tetradynamous_, when, being only six, four of them surpass the other two, as in the Mustard-flower and all the Cruciferous family, Fig. 235.

286. =The Filament= is a kind of stalk to the anther, commonly slender or thread-like: it is to the anther nearly what the petiole is to the blade of a leaf. Therefore it is not an essential part. As a leaf may be without a stalk, so the anther may be _Sessile_, or without a filament.

287. =The Anther= is the essential part of the stamen. It is a sort of case, filled with a fine powder, _the Pollen_, which serves to fertilize the pistil, so that it may perfect seeds. The anther is said to be

_Innate_ (as in Fig. 292), when it is attached by its base to the very apex of the filament, turning neither inward nor outward;

_Adnate_ (as in Fig. 293), when attached as it were by one face, usually for its whole length, to the side of a continuation of the filament; and

_Versatile_ (as in Fig. 294), when fixed by or near its middle only to the very point of the filament, so as to swing loosely, as in the Lily, in Grasses, etc. Versatile or adnate anthers are

_Introrse_, or _Incumbent_, when facing inward, that is, toward the centre of the flower, as in Magnolia, Water-Lily, etc.

_Extrorse_, when facing outwardly, as in the Tulip-tree.

288. Rarely does a stamen bear any resemblance to a leaf, or even to a petal or flower-leaf. Nevertheless, the botanist's idea of a stamen is that it answers to a leaf developed in a peculiar form and for a special purpose. In the filament he sees the stalk of the leaf; in the anther, the blade. The blade of a leaf consists of two similar sides; so the anther consists of two LOBES or CELLS, one answering to the left, the other to the right, side of the blade. The two lobes are often connected by a prolongation of the filament, which answers to the midrib of a leaf; this is called the CONNECTIVE. This is conspicuous in Fig. 292, where the connective is so broad that it separates the two cells of the anther to some distance.

289. A simple conception of the morphological relation of an anther to a leaf is given in Fig. 295, an ideal figure, the lower part representing a stamen with the top of its anther cut away; the upper, the corresponding upper part of a leaf.

290. So anthers are generally _two-celled_. But as the pollen begins to form in two parts of each cell (the anterior and the posterior), sometimes these two strata are not confluent, and the anther even at maturity may be _four-celled_, as in Moonseed (Fig. 296); or rather, in that case (the word _cell_ being used for each lateral half of the organ), it is _two-celled_, but the cells _bilocellate_.