NASTURTIUM. 



93 



characteristics, both of organic structure and chemical composition, than 

 this ; and hence to know a single plant of the family well — for example, 

 mustard — is to know them all. Many of them — for instance, the cabbage 

 and turnip — have been modified to a considerable extent by long cultiva- 

 tion, and have become valuable articles of food. 



NASTURTIUM. 



Character of the Genus. — Pod a silique or silicle, linear-oblong or glob- 

 ular, nearly or quite round. Seeds small, numerous, marginless, in two 

 irregular rows in each cell. Cotyledons accumbent. Annual, biennial, or 

 perennial herbs, aquatic or growing in marshes and wet places, with white 

 or yellow flowers, and com- 

 monly smooth, shining, pin- 

 nate or pinnatifid leaves. 



Nasturtium officinale 

 Eobert Brown. — Water -cress. 



Description. — Calyx : se- 

 pals ovate, caducous. Co- 

 rolla : petals white, twice the 

 length of the sepals. Siliques 

 one-half to two-thirds inch 

 long, bending upward, more 

 or less, on divergent, ascend- 

 ing pedicels, of nearly the 

 same length. Eoot biennial, 

 long, and creeping. Stem 

 spreading and rooting. 

 Leaves pinnate ; leaflets 3 to 

 11, roundish or oblong, near- 

 ly entire, the terminal one 

 largest. 



Habitat. — Introduced from 

 Europe, where it has long been cultivated as a salad. Escaping from cul- 

 tivation here, it has become established in brooks and ditches. 



Nasturtium Armoracia Fries (Gochlearia Armor •acia'Lhmt). — Horse- 

 radish. 



Description. — Calyx : sepals ovate, obtuse, caducous. Corolla : petals 

 white, twice the length of the sepals. Style very short, persistent. Pod 

 nearly globular, about 4-seeded, seldom attaining perfection here or in 

 Britain. Root perennial, large, tapering, G to 12 inches long. Stem erect, 

 2 to 3 feet high. Radical leaves long and large, crenate, seldom pinnat- 

 ifid : stem-leaves smaller and narrower than the radical, the lower ones 

 7 



Fig. 107.— Nasturtium officinale. 



