POLYPETAL^— VIOLACE^ 127 



genus, because the flowers, fruits, and seeds are closely alike. 

 The Cabbage (Brassica oleraced) is cultivated for the sake of 

 its large leaves. The Brussels-sprouts is merely a variety of 

 cabbage producing many large green axillary buds which form 

 the edible portions. The Cauliflower and Broccoli are other 

 varieties of the cabbage, cultivated for the sake of their much- 

 branched inflorescences, the stems of which are fleshy and 

 colourless, the flowers being reduced to minute buds. The 

 "heart" of a Cauliflower or Broccoli is a branched terminal 

 inflorescence. The Turnip (Brassica campestris) is a biennial 

 possessing a tuberous main root, which we eat as a vegetable. 

 The Swede is a variety of the Turnip, also cultivated for the 

 sake of its swollen tap-root. The Rape is still another variety 

 of B. campestris, and from its seeds colza-oil is obtained. The 

 seeds of the Black Mustard {Brassica nigra) are the source of 

 the condiment mustard. We use the young plants of the 

 White Mustard {Brassica alba) in the composition of salads ; 

 this is the Mustard cultivated with Cress to form "mustard and 

 cress." Cress {Lepidium sativum) is also one of the Cruciferse. 

 The edible part of the-Horse-Radish {Cochlearia armoracia) is 

 the rhizome (not the root) : the leaves of the Horse-radish are 

 stipulate. The swollen red tubers of the Radish {Raphanus 

 sativus) are formed mainly by the hypocotyl. Water-cress 

 {Nasturtium officinale) also belongs to this family. A few 

 Cruciferse are cultivated in gardens for the sake of their 

 flowers ; such are the Stocks, Candytuft (with zygomorphic 

 flowers). 



VIOLACEiE (Violet Family) 



Herbs. Lea^ves alternate, stipulate. Flowers often showy, 

 irregular, hypogynous. Sepals five, polysepalous. Petals five, 

 polypetalous. Stamens five. Carpels three, syncarpous ; ovary 

 one-chambered, with three parietal placentae bearing many 

 ovules. Fruit, a three-valved capsule. 



Type : PANSY ( Viola tricolor). 



Vegetative characters. — Herb. Stem branched, with or with- 

 out a rhizome. Leaves alternate, stalked; stipules large, 

 leaf-like. Leaves rolled towards their upper faces in the bud. 

 Inflorescence. — The flower is solitary, axillary. Note the two 

 prophylls (fig. 158-3, /r) inserted at a considerable distance up 



