554 BOTANY. 



Race V. Kohl-Babi, in which the short and few-leaved stem becomes, 

 thick, bulbous, and edible. 



B. campestris, of the same regions as the preceding, has given rise to 

 the various kinds of Turnips. Colza and Rape also are probably vari- 

 eties ; the latter are extensively cultivated in Europe for their oily- 

 seeds, from which useful oils are obtained by pressure. 



Baphanus aativus, the Radish, is a native of Cliina. 



Nasturtium ArTnorada, the Horseradish of Europe, has long been 

 cultivated for its pungent roots, which are used as a condiment. Ac- 

 cording to Dr. Gray, the plant, for some unknown reason, does not pro- 

 duce seeds in this country. 



N. officinale. Water Cress of Europe, and now run wild in many parts 



I'iGS. 536-41.— Seeds op Cbcciteii^. 



Wi6. 537. 



Fio. 541. 

 Fig. 639. 



Fig. 536.- Seed of Erysimum. Magnified. 

 Fig. 637.— Lcingitudinal section of seed. Magnified. 



Fig. 538. — Cross-section of seed, sliowing incumbent Cotyledons. Magnified. 

 Fig. 539. —Longitudinal section of seed of AraUe. Magnified. 

 Fig. 540.— Cross-section of seed otArabis, accumbent cotyledons. Magnified. 

 Fig. 641. — Cross-section of seed of BaTbarea^ imperfectly accumbent cotyledons. 

 Hagnified. 



of the TTnited States, and many other rapidly growing foreign and na- 

 tive species, are used as salads. 



Brassica alba, White Mustard, and B. nigra. Black Mustard, both 

 natives of Europe, are grown for their seeds, which when ground con- 

 stitute the common condiment Mustard. It is also of considerable- 

 value in medicine. 



Isatis tinetoria, » tall-growing European biennial, was formerly ex- 

 tensively grown for the blue dye obtained from it. 



The most important ornamental plants of the order are the Wall- 

 flower {Oheirantlms), Gilly Flower or Brompton Stock (Matthiola), 

 Rocket (Hesperis), Candytuft (Iberis), Honesty (Lunaria), Sweet Alys- 

 sum {Alyssum), etc., etc. 



Several of the species are troublesome weeds— e g.. Shepherd's Purse 

 (Oapsella), which has come to this country from the Old World ; Pepper- 

 grass (Lepidium), native and introduced ; False Flax (Uamelina) from. 

 Europe ; Charlock and Mustard (Brassica) from Europe. 



