366 THE KINDS OF PLANTS 



B. nigra, Koch. Black mustard. Fig. 518. Leaves pinnatifid, some- 

 what hairy: pod short, strongly 4-angled, not hairy. Mustard (flour) comes 

 largely from this species. 



B. alba, Boiss. White mustard. Leaves pinnatifid, and rough -hairy: 

 pods rather slender, hairy, but only the lower part seed-bearing. 



B. arvensis. Kuntze. Charlock. Leaves strongly toothed, 

 pod knotty, hairy or smooth, the upper third indehiscent and 2- 

 edged. Fig. 413. 



2. BARBAREA. Winter Cress. 



Low herbs, blooming in early spring, with many small light 

 yellow flowers, and lyrate leaves with the terminal division much 

 the largest: pod cylindrical or somewhat 4-angled, the valves 

 having a strong midvein: seeds a single row. 



B. vulgaris, R. Br. Common winter cress. Yellow rocket. 

 Biennial, about 1 ft. high, with smooth foliage and flowers in 

 elongating clusters: lower leaves lyrate, upper ones cut or merely 



toothed. Low grounds. 

 or». 

 Brassica 3 MATTHiOLA. Stock. Gilliflower. 

 nigra. 



Cultivated garden or house plants from Europe: stems and 

 leaves hoary-pubescent: flowers showy, single or double, of many colors, 

 fragrant, in terminal racemes; stigma deeply 2-lobed: silique nearly cylin- 

 drical, with prominent midrib on each of the 2 valves; seeds winged. 



M. incana, R. Br. Biennial or perennial with stout, rather woody stem: 

 leaves lanceolate, entire: flowers white, varied shades of red, purple, etc. 

 Much grown in gardens and greenhouses. 



4. ARABIS. Rock Cress. 



Mostly very small herbs with purple or white flowers: stems leafy: rad- 

 ical leaves spatulate, the stem-leaves sessile: siliques very narrow, elongated, 

 flat, the valves smooth, keeled or one-nerved in the middle, or veined length- 

 wise; seeds in 1 or 2 rows in each cell, flattened, usually margined or winged. 



A. canadensis, Linn. Sickle-pod. Biennial with stems erect, 1-3 ft.: 

 leaves lanceolate, pointed at both ends, simple, toothed or entire, sessile, 

 pubescent: flowers small, white, petals twice as long as sepals: pods long, 

 flat, sickle-shaped, pendent on hairy pedicels; seeds broadly winged. Com- 

 mon in woods and rocky ravines. 



A. glabra, Bernh. Biennial tall, 2-4 ft., glaucous above, but pubescent 

 at base, with many stem-leaves, ovate-lanceolate, 6essile, sagittate-clasping 

 at base; petals yellowish white, scarcely longer than the calyx: pods narrow, 

 erect: seeds in 2 rows, marginless. Fields and rocky places. 



5. DENTARIA. Toothwort. 



Low herbs, perennial, found in damp woodland, blooming with the early 

 spring flowers, bearing flowers in corymbs, white, roseate or purplish, 

 larger than the similar flowers of Cardamine: rootstocks long, horizontal, 



