Family 11. Cistifloræ.

The flowers in this family are perfect, regular (except Resedaceæ, Violaceæ), hypogynous, the perianth-leaves free (a few have them slightly united), æstivation most frequently imbricate; they are eucyclic in the andrœcium, and most frequently in the other parts, and generally 5-merous with S5, P5, A5 + 5, G3, but other numbers also occur; several have indefinite stamens, but the stamens arise (where the development is known) in centrifugal order and are arranged, often very distinctly, in bundles; in other words, the large number of stamens is formed by the splitting of a small number (most frequently 5); a true spiral arrangement is never found. Gynœceum syncarpous, multicarpellary (Dilleniaceæ and a few Resedaceæ are apocarpous), most frequently the number of carpels is 3, forming a unilocular ovary with parietal placentæ, but parallel with this, multilocular ovaries, with the ovules placed in the inner angle of the loculi, are also found, and a few genera have a free, centrally-placed placenta. The fruit is most frequently a capsule. The dehiscence is never with a “replum,” i.e. the persistent frame of the placenta, as in the family Rhœadinæ. One half of the orders has endosperm (Violaceæ, Cistaceæ, Droseraceæ, Bixaceæ, Ternstrœmiaceæ, etc.), the other has no endosperm (Resedaceæ, Hypericaceæ, Elatinaceæ, Tamaricaceæ, etc.); some have a curved, the majority a straight embryo. The family is scarcely quite natural; in the future the orders will probably be arranged differently.

Order 1. Resedaceæ (Mignonettes).—Herbs or small shrubs with spirally-placed leaves and very small, gland-like stipules (as in Cruciferæ); the ☿, hypogynous flowers are zygomorphic, and arranged in racemes or spikes typically without bracteoles. The zygomorphic structure is produced by the greater development of the posterior side of the flower, especially the petals and the nectary (“disc,” in Fig. 416 d) which is situated between the petals and stamens; in general there are 5–8 free sepals and petals, the latter consisting of a large scale-like sheath with a fimbriated blade (see Fig. 416); stamens numerous; carpels 6–2 united together; ovary unilocular with parietal placentæ, but the cavity of the ovary is not closed at the top. In Astrocarpus the gynœceum is apocarpous. The fruit is most frequently a capsule; the seeds are reniform, without endosperm, and the embryo is curved.

Order 2. Droseraceæ (Sundews). Herbs, chiefly living on moors or in water, and whose leaves are adapted to catch and digest small animals. With regard to the flower, they are closely allied to the Violaceæ, especially to those with regular flowers. Drosera (Sundew) has a long-stalked scorpioid cyme with regular, ☿, hypogynous flowers, 5-merous as in Viola. S5, P5, A5, G3 (in a syncarpous gynœceum, with free, bifid styles and basal or parietally-placed ovules in the unilocular ovaries). The capsule opens also as in Viola, but, among other differences, the styles are free, the seeds very small, and surrounded by a loosely lying, thin shell. Drosera has radical, long-stalked leaves with the blade (Fig. 417) covered by numerous strong glandular hairs, placed on the edge and in the middle; when small animals are caught by these hairs, the latter and the entire blade close slowly over them dissolving and absorbing all the digestible matter as nourishment.

Order 5. Violaceæ (Violets). The flowers are ☿, and generally zygomorphic, hypogynous, with S5, P5, A5, G3 (Fig. 421). The stamens are closely applied to the ovary, they have a very short filament, and at their summit generally a membranous appendage formed by the prolongation of the connective (Fig. 422 g). The ovary is unilocular with 3 parietal placentæ; style undivided (Fig. 422 B). The fruit is usually a 3-valved capsule, opening along the dorsal sutures (Fig. 423). Embryo straight; endosperm fleshy (Fig. 425).—Many are herbaceous plants (e.g. Viola), but in the Tropics shrubs are also found (e.g. Ionidium); a few are lianes; the leaves are scattered, with stipules, and involute in the bud.

Viola. The sepals are prolonged backwards beyond the point of insertion (appendiculate); the corolla is polypetalous, descending imbricate, and zygomorphic, its anterior petal being larger than the others and provided with a spur (Fig. 421). The 2 anterior of the 5 almost sessile stamens are provided with a spur-like nectary, which protrudes a considerable distance into the petaloid spur (Figs. 421, 422 n, sp). The style is club-like, and bears the stigma in a groove on the anterior side (Fig. 422 st). Herbs with rhizomes, or annuals; flowers solitary. V. odorata, canina, etc., have cleistogamic flowers which produce fruit in addition to the large, coloured (violet) flowers. The Pansy (V. tricolor) has large flowers adapted for insect-pollination, and also smaller, less conspicuous ones designed for self-pollination. The stigma, as in Fig. 422 A, st, and B, is situated on the anterior side of the stylar-head, immediately in front of the channel leading down to the spur (sp); below it is situated a valve, easily covered with pollen when the proboscis of an insect is introduced into the spur, but which closes upon its withdrawal; cross-pollination is thus secured.—The sweet-scented V. odorata is visited by the honey-bee, which insures cross-pollination, and in the absence of insect visits it effects self-fertilisation by cleistogamic flowers. The conspicuous but scentless V. tricolor, var. vulgaris, is less frequently visited by insects (humble-bees). In V. silvatica and V. canina the pollen is carried on the head or proboscis of the honey-sucking bee.—The fruits of V. odorata bury themselves slightly in the soil. In the others the fruits are raised above the ground; the 3 boat-shaped valves close together along the central line, and eject the seeds, one by one, with much violence, so that they are thrown to a great distance.

Order 8. Cistaceæ. Shrubs or herbs, natives especially of the Mediterranean region. Flowers generally in raceme-like scorpioid cymes, regular, ☿, hypogynous; sepals 5, free, twisted in the bud, of which the two outer are generally much smaller than the others; petals 5, free, twisted in the bud (in the direction opposite to the sepals), fugacious; stamens numerous; gynœceum syncarpous, carpels usually 3–5, style simple, ovary unilocular, with parietal placentation (seldom divided into loculi, with axile placentation). The ovules are orthotropous in opposition to some of the other orders of this family. The capsule dehisces along the dorsal sutures; embyro curved. The leaves are simple, undivided, generally opposite and stipulate.—They are Violaceæ with regular flowers, numerous stamens, and curved embryo. The numerous stamens are in reality only one or two 5-merous whorls, divided into a large number of stamens; these are formed, therefore, in descending order, like the lobes of many compound foliage-leaves.

Helianthemum (Rock-Rose), has 3 carpels.—Cistus has 5 (-10) carpels.

Order 12. Hypericaceæ (St. John’s-worts). This order is recognised by its always opposite or verticillate, simple, and entire, penninerved leaves, without stipules, and usually dotted with pellucid glands; by the always ☿, regular, hypogynous flowers in a cymose inflorescence; the generally 5-merous calyx and corolla, with sepals and petals free; the stamens 3–5, numerously branched (Figs. 426, 427); and the gynœceum, 3–5-carpellate, styles usually free. The ovary is 3–5-locular, or unilocular with 3–5 parietal placentæ. Fruit a capsule (dehiscing septicidally) or berry. Endosperm absent.

Hypericum. Some species have a square stem; in these cases the leaves are placed opposite the edges. Fruit a capsule.—Vismia has a berry.—The flowers of Hypericum have no honey, and supply only pollen; self-pollination often takes place.

Order 14. Ternstrœmiaceæ. Trees and shrubs with scattered, simple, and often more or less leathery, evergreen, penninerved leaves, without stipules (Fig. 428). The two most important genera are: Camellia and the closely allied Thea (by some authorities these are united into one genus). The flowers are regular, hypogynous, and situated singly on very short stalks. A number of green floral-leaves are placed below the calyx and gradually pass over into the sepals, and the leaves (5–6) of the calyx again gradually pass over into the corolla (this being especially marked in Camellia), of which the number of leaves varies (5, 6, 7 and upwards); the calyx and the corolla are acyclic or eucyclic; the petals are slightly united at the base; stamens numerous in many whorls, the external ones are arranged in bundles and united with the petals as in the Columniferæ; gynœceum syncarpous; styles often free nearly to the base; ovary 3–5-locular, ovules numerous in each loculus. The fruit is a woody capsule.—Other genera show more distinctly than these the same structure as in the preceding orders, namely: S5, P5, A5 + 5, of which the calyx-stamens are often suppressed, and the petal-stamens divided into numerous stamens.—Kielmeyera (S. Am.)

Family 12. Gruinales.

The flowers are hypogynous, ☿, polypetalous, usually regular (except Pelargonium, Tropæolaceæ, Balsaminaceæ) and throughout 5-merous: S5, P5, A5 + 5, or 5 + 0, G5 (epipetalous). The stamens soon fall off and are obdiplostemonous, often united at the base (monadelphous); the corolla-stamens are in some completely suppressed (e.g. Balsaminaceæ, Fig. 438), in others reduced to teeth (Linum, Fig. 431; Erodium). The Tropæolaceæ have 3 carpels and only 8 stamens (Fig. 437). Ring-like nectaries are not present, but at most only glandular bodies, borne outside the base of the stamens. Ovaries many-locular. The ovules as a rule are pendulous, with the micropyle directed outwards (Fig. 431, B), and the radicle therefore also points outwards. Usually herbs. Related to the Columniferæ.

Order 1. Oxalidaceæ. Most of the species are herbs with rhizomes; the leaves are stalked, compound, with entire leaflets which are folded and bent backwards in the bud (and in the sleep position), exstipulate; some species have sensitive leaves. The flowers (Fig. 429) are regular, and have S5, P5, which are twisted to the left or right in æstivation, A5 + 5, all united at the base (monadelphous), gynœceum 5-carpellate, styles 5 free, stigmas capitate, ovary 5-locular, ovules numerous. The fruit is a capsule opening with clefts on the dorsal sutures through which the seeds are ejected, while the fleshy, external layer of the testa springs off elastically. Embryo straight. Endosperm.

Order 2. Linaceæ. Herbs with scattered or opposite, sessile, simple, small, entire leaves, without (rarely with small) stipules. The flowers (Fig. 430) are regular, 5- or 4-merous. Petals are free, twisted, quickly falling off. Stamens united at the base; the petal-stamens are either reduced to teeth (Fig. 431 A, m) or entirely suppressed. Styles free. The (5–4) epipetalous loculi of the ovary are incompletely halved by false divisional walls, each half contains one ovule (Fig. 431 C). The fruit is a spherical capsule, dehiscing along the divisional wall (Fig. 432); the 10 (-8) seeds have a straight embryo and very slight endosperm (Fig. 433).

Linum (Flax) has 5-merous flowers. The main axis terminates in a flower; and the succeeding branching is cymose, or unipared scorpioid branching by unilateral development, and the flowers in consequence of the vigorous sympodial development of the lateral axis (and also by the leaves being displaced and pushed aside), assume a position apparently lateral (i.e. racemose) without bracts; each branch of the sympodium generally has 2 leaves. The testa is shining and smooth when dry, but its external cellular layer becomes mucilaginous in water.—Radiola has a 4-merous flower. It is a small herb with opposite leaves, and regular, dichasial branching.

Order 3. Geraniaceæ. The majority are herbs with dichasial branching, and scattered or opposite, stalked, palminerved (rarely penninerved) leaves with small stipules. The flowers are regular (except Pelargonium) and 5-merous, with 10 or 5 stamens, which are slightly united at the base. Nectaries alternate with the corolla-stamens. The ovary is most frequently 5-locular, deeply 5-grooved, and bears 1 well developed style (“beak”), which towards the apex divides into 5 branches bearing stigmas; ovules 1 in each loculus, pendulous or ascending. The 5 carpels become detached from one another when ripe, and bend or roll back (Fig. 434) or become spirally twisted in the upper “beak-like” part (Figs. 435, 436), whilst a central column (septal column) persists; each carpel, in consequence, remains either closed, and the fruit is a 5-merous schizocarp whose nut-like lower portion, containing the seed, is forced into the ground, thus burying the seed by the movements of the spirally-twisted, hygroscopic “beak” (Figs. 435, 436); or it opens along the ventral suture, so that the seeds may fall out, and it is then a 5-valved capsule, with septicidal dehiscence (Fig. 434) and the rolling up often takes place so suddenly and violently that the seeds are shot out to considerable distances. The embryo is usually green and curved, and the cotyledons are folded; endosperm is wanting.

Geranium (Crane’s-bill) has 5 + 5 stamens,and a septicidal capsule; the carpels most frequently remain suspended from the apex of the column (Fig. 434). The leaves are most frequently palminerved. The flowers are situated solitarily or 2 together (2-flowered scorpioid cyme).—Erodium (Stork’s-bill); inflorescence a many-flowered unipared scorpioid cyme, stamens 5 + 0 (petal-stamens are wanting), and fruit a schizocarp whose carpels become detached; their beaks are hairy on the internal surface and twist themselves spirally (Fig. 436). The umbellate inflorescences are composed of multiflowered scorpioid cymes. The leaves are often penninerved.—The most primitive type is represented by Biebersteinia: S5, P5, A5 + 5, G5 (ovaries free, and styles united above); fruit 5 small nuts. The most advanced type is Pelargonium, which has zygomorphic flowers, the posterior sepal being prolonged into a spur which becomes adnate to the peduncle; the petals are unequal in size; some of the petal-stamens are often wanting. (Erodium may be slightly zygomorphic).

Order 4. Tropæolaceæ. Herbaceous, juicy plants which have scattered, long-stalked, peltate leaves without stipules, and often climb by their sensitive petioles. The flowers are situated singly in the axils of the foliage-leaves on long stalks, and are zygomorphic, the receptacle under the posterior sepal being prolonged into a spur; there are also differences between the posterior and anterior petals, the 2 posterior petals situated on the border of the spur being perigynous, and the edge of the anterior petals adjoining the claw fringed. After the 5 sepals (which are more or less coloured) and the 5 petals, follow 8 stamens (as the 2 median ones are suppressed, one from each whorl) and a gynœceum formed of 3 carpels; in each of the 3 loculi of the 3-grooved ovary is 1 ovule. The fruit is a schizocarp and divides into 3 1-seeded, drupe-like fruitlets, which do not (as in the Geraniaceæ) leave any pronounced column between them. Endosperm is wanting. The cotyledons are thick and sometimes slightly coalescent. Tubers often occur.

Tropæolum.—About 40 species; all from America.

Order 5. Balsaminaceæ. Herbaceous, chiefly annual plants with juicy, brittle stems, so transparent that the vascular bundles may be distinctly seen. The leaves are simple, usually scattered, penninerved and dentate; stipules are wanting, but sometimes large glands are present in their place at the base of the petioles. The flowers are strongly zygomorphic; of their five 5-merous whorls the petal-stamens are suppressed (S5, P5, A5 + 0, G5); the sepals are coloured, the 2 anterior ones (Fig. 438 3, 5) are very small or entirely suppressed, the posterior one is very large and elongated into a spur, and the 2 lateral ones pushed forward; sometimes the weight of the spur turns the flower completely round, so that the posterior leaves assume an anterior position; apparently only 3 petals, since the lateral and the posterior petals become united in pairs, and the anterior is larger and differently shaped; the 5 stamens have very short and thick filaments united at the base, and their anthers finally adhere together and remain in this condition, covering over the gynœceum; the filaments ultimately rupture at the base, and the entire anthers are raised on the apex of the gynœceum as it grows up. The gynœceum has a sessile stigma and a 5-locular ovary. The fruit is a capsule which, on maturity, opens suddenly when irritated, dividing into valves from the base upwards, and as the 5 valves roll up elastically, the seeds are shot out on all sides to considerable distances; a central column persists (Fig. 439). The embryo is straight, and without endosperm.