554 



BOTANY. 



Race V. Kohl-Robi, 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. 



Raphanus satimis, the Radish, is a native of China. 



Nasturtium Armoracia, 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. offlcinale, Water Cress of Europe, and now run wild in many parts 



FIGS. 536-41. SEEDS OF CBUCIFEIUE. 



Fie. 537. 



Fro. 540. 



FIG. 541. 



FIG. 539. 



Fig. 536. - Seed of Erysimum. Magnified. 

 Fig. 537. Longitudinal section of seed. Magnified. 



Fig. 538. Cross-section of seed, showing incumbent cotyledons. Magnified. 

 Fig. 539. Longitudinal section of seed of Arabis. Magnified. 

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

 Fig. 541. Cross-section of seed of Barbarea, imperfectly accumbent cotyledons. 

 Magnified. 



of the United 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 tinctoria, a tall-growing European biemiiul, was formerly ex- 

 tensively grown for the blue dye obtained from it. 



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

 flower (Cheiranthus), Gilly Flower or Brompton Stock (Matthiola), 

 Rocket (Hesperis), Candytuft (Iberis), Honesty (l/unaria), Sweet Alys- 

 sum (Alyssum), etc., etc. 



Several of the species are troublesome weeds eg., Shepherd's Purse 

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

 grass (Lepidiuni), native and introduced ; False Flax (Camdinn) troin 

 Europe ; Charlock and Mustard (Brassica) from Europe. 



