130 species; mostly from the northern temperatures.
Pollination. Fumaria, with its inconspicuous flowers, has to a great extent to resort to self-pollination. Corydalis, on the other hand, is dependent on cross-pollination; C. cava is even absolutely sterile with its own pollen. Corydalis is pollinated by insects with long probosces (humble-bees, bees), which are able to reach the honey secreted in the spur; as they alight on the flowers they press the exterior petals on one side (Fig. [396] e), so that the stigma, surrounded by the anthers, projects forward; the proboscis is introduced in the direction of the arrow in the figure, and during this act the under-surface of the insect is covered with pollen, which is transferred by similar movements to the stigma of another (older) flower.—Ornamental plants; Dicentra (spectabilis and eximia), Adlumia, Corydalis.
Order 3. Cruciferæ (Crucifers). The flowers are regular, ☿; sepals 4, free (2 + 2), deciduous; petals 4, free, deciduous, unguiculate, placed diagonally in one whorl, and alternating with the sepals; stamens 6; the 2 outer are short, the 4 inner (in reality the two median split to the base) longer, placed in pairs (tetradynamia of Linnæus); gynœceum syncarpous formed by 2 (as in the previous order, lateral) carpels, with 2 parietal placentæ, but divided into two loculi by a spurious membranous dissepiment (replum) (Fig. [397]). Style single, with a capitate, usually two-lobed stigma, generally commisural, that is, placed above the parietal placentæ (Fig. [397]), but it may also be placed above the dorsal suture, or remain undivided. Ovules curved. The fruit is generally a bivalvular siliqua (Fig. [398] B, C), the valves separating from below upwards, and leaving the placentæ attached to the replum; other forms of fruits are described below. The oily seeds have no endosperm (endosperm is present in the two previous orders); the embryo is curved (Figs. [398] E, F; [399], [400]).—In general they are herbaceous plants, without latex, with scattered, penninerved leaves, without stipules; the inflorescence is very characteristic, namely, a raceme with the flowers aggregated together at the time of flowering into a corymb, and destitute of both bracts and bracteoles.
Fig. 397.—Diagram of a Cruciferous flower.
Fig. 398.—Brassica oleracea: A raceme; B, C siliqua; D seed; E embryo; F transverse section of seed.
Fig. 399.—Transverse section of seed and embryo of Cheiranthus cheiri.
