l6o Elementary Botany 



widely distributed order, easily recognised by the cruciform 

 corolla and tetradynamous stamens. ITo plant of this order 

 is poisonous. Manyare used for food purposes. Many^of the 

 plants contain sulphur and are pungent in taste. 



Principal Plants of the Order. 



Brassica.. A large and important genus. Leaves irregularly 

 pinnate ; flowers yellow ; fruit a siliqua, often beaked at the end. 

 Principal species are — B. Sinapis, Mustard ; B. oleracea, which 

 yields all the varieties of Cabbage, Cauliflower, Broccoli, 

 Brussels Sprouts, and Savoys ; B. JVapus, Rape ; B. campestris, 

 Swedish Turnip, the seeds of which with some other species 

 yield colza oil ; B. Napa, Turnip. 



Capsella (fig. 102), Shepherd's -purse. One of the com- 

 monest weeds, and a good example of a silicula-bearing 

 crucifer. Flowers small, white; fruit a silicula with replum 

 running across the narrow diameter (angustisept) (fig. 297, 11.). 



Cheiranthus, Wallflower. 



Cochlearia. Fruit a silicula with replum running across the 

 broad diameter (latisepl) (fig. 297, iii.), so that the fruit is 

 nearly globose. There are two British species, the Horse- 

 radish and the Scurvy-grass. 



Crambe, Sea-kale. Fruit two-jointed, upper joint with one 

 seed indehiscent, lower joint forming a stalk above the calyx ; 

 might be mistaken for a gynophore. 



Iberis, Candytuft. Petals unequal, the two exterior petals 

 larger than the interior ones ; fruit silicula, angustiseptate. 



Jsatis, Dyer's-woad. Small numerous yellow flowers ; fruits 

 pendulous, flattened, indehiscent. The plant yields a blue dye. 



Zepidium, Cress. Numerous small white flowers, petals 

 equal ; fruit silicula, angustiseptal, one seed in each cell. 



Matthiola, Stock. Plants hoary from minute hairs ; large 

 purple flowers ; fruit a cylindrical siliqua. 



Nasturtium, Watercress. Small yellow or white flowers ; 

 fruit a siliqua, generally somewhat curved. (This must not be 

 confounded with the garden Nasturtium, which is a Tropseolum, 

 belonging to quite a different order.) 



Raphanus, Radish. Fruit a lomentum. 



