398 DICOTYLEDONES. 



movements to the stigma of another (older) flower. Ornamental plants ; 

 Dicentra (spectabilis and eximia), Adlumia, Corydalis. 



Order 3. Cruciferse (Crucifers). The flowers are regular, 

 5; 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 (tetrady- 

 namia of Linnaeus) ; gynceceum syncarpous formed by 2 (as in the 

 previous order, lateral) carpels, with 2 parietal placentae, 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 placentas (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 separat- 

 ing from below upwards, and leaving the 

 placentae 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 

 FIG. 397.-Diag.-am of a j s yerv characteristic, namely, a raceme 



Cruciferous flower. 



with the flowers aggregated together at the 



time of flowering into a corymb, and destitute of both bracts and 

 bractt'oles. 



Many are biennial, forming in the first year a close leaf-rosette. By culti- 

 vation the tap-root can readily be induced to swell out into the form of a tuber 

 (Turnips, Swedes, etc.). Stipules are found indicated by small glands on the 

 very young leaves ; in Cochlearla armoracia they are fairly large triangular 

 scales. Stellate hairs often occur. Floral-leaves are occasionally developed. 

 Terminal flowers are never found in the inflorescences. Iberis and Teesdalin. 

 have zypomorphic flowers. Subularia (Fig. 403) is perigynous. The 2 external 

 sepals (Fig. 397) stand in the median plane ; it may therefore be supposed that 

 there are two bracteoles outside tbese which, however, are suppressed, and can 

 only in a few instances be traced in the young flower ; the two lateral sepals 

 are often gibbous at the base, and serve as reservoirs for the nectar secreted 

 by the glands placed above tbem ; they correspond in position to the extemal 

 petals of the Fumariaceas. The 4 petals.which follow next arise simultaneously, 

 : and alternate with the 4 sepals; if it could be shown that these are merely 2 

 median petals, which have been deeply cleft and the two parts separated from 



