238 SYSTEMATIC BOTANY 



hood, enclosing two nectaries, which are modified petals. 

 In the two latter the flowers are zygomorphic. Floral for- 

 mula : k 5 or 3, c 0-5 or 00, a 5- 00, gi-oo. 



The nectaries of the Christmas Rose, Winter Aconite 

 (Eranthis), Love-in-a-Mist (Nigella), Monkshood, and Aconite 

 are known as ' honey-leaves ', and are probably derived 

 from stamens. 



Order Cruciferae. Sepals and petals four each. Sta- 

 mens six, in two whorls, two outer short, and four 

 inner long ones (tetradynamous). Pistil superior of 

 two carpels (syncarpous), two-celled, divided by 

 a partition (replum). Fruit, a siliqua or silicula 

 (Figs. 1-5). 



This order contains upwards of 200 genera and 1,200 

 species widely distributed throughout the North Temperate 

 and Mediterranean regions. They are mostly herbaceous 

 perennials, but some are annuals, and others are biennials. 

 The leaves are without stipules ; the inflorescence is 

 a raceme or corymb, and is usually without bracts. 



Very many cultivated plants belong to this order, e. g. 

 the Cabbage (Brassica oleracea), from which many useful 

 varieties have been derived by cultivation and selection, 

 such as Red Cabbage, Kale, Savoy, Brussels Sprouts, in 

 which the axillary buds become small cabbages. In the 

 Broccoli and Cauliflower the inflorescence becomes abnor- 

 mally branched and fleshy, and the Kohlrabi is a tuberous 

 stem or corm. 



From other species of Brassica are derived the Turnip 

 and Swede ; the Radish, Horse-Radish, Watercress, 

 Garden Cress, and Mustard, also belong to this order, as 

 well as some of the commonest weeds of cultivation, e. g. 

 Charlock and Shepherd's Purse ; while others are culti- 

 vated for their flowers, for example, Wallflower, Stock, 

 Candytuft, Honesty, Arabis, and Aubretia. 



