POLYPETAL^— CRUCIFER^ 



125 



Sepals, 2 + 2, polysepalous. Petals, 4, polypetalous. Stamens, 

 2 + 4, two short and four long. Carpels, 2, syncarpous : 

 ovary, divided by a false septum connecting two parietal 

 placentae ; ovules numerous. Fruit usually a siliqua. Seed, 

 no endosperm. 



Type I. : WALLFLOWER {Cheiranthus cheiri).* 



Vegetative characters. — A perennial herb, slightly woody 

 at the base. Leaves alternate, exstipulate, simple. Inflores- 

 cence : a raceme without bracts. Note the absence of 

 prophylls from the flower -stalks. Flower (fig. 156) actino- 



156 IS7 



Fig. 156. — Vertical section of flower of Wallflower. 

 Fig. 157. — Floral diagram of ditto. 



morphic, hypogynbus, brown or yellow, sweet-scented. Sepals 

 2-1-2, separate. The four sepals are arranged in two alternating 

 whorls of two each. The two lateral sepals {c) form the inner 

 whorl, and are inserted higher on the receptacle than the two 

 outer median sepals. The lateral sepals are slightly enlarged 



* Almost any Crucifer will serve in place of the Wallflower, so uniform 

 is the structure of the flowers, excepting as regards the nectaries. 



