96 FOUNDATIONS OF BOTANY 



2. B. juncea, Coss. Similar to the preceding, but nearly or quite 

 smooth. Pedicels slender. Beak of the cylindric pod slender, 

 conical, not containing a seed. Recently introduced from Asia and 

 becoming very abundant eastward. 



3. B. alba, Boiss. WHITE MUSTARD. Stem 2-5 ft. high, with 

 reflexed hairs. Upper leaves pinnately cut. Pods borne on spread- 

 ing pedicels, bristly, with a sword-shaped, 1-seeded beak occupying 

 more than half their length. Seeds pale. Cultivated from Europe 

 and introduced to some extent. 



4. B. nigra, Koch. BLACK MUSTARD. Stem 3-6 ft. high, some- 

 what hairy. Lower leaves lyrate with the terminal lobe much the 

 longest, stem-leaves linear-lanceolate, entire or toothed, smooth. 

 Pods awl-shaped, 4-angled, smooth, lying against the stem. Seeds 

 brownish, more biting than in No. 2. Cultivated from Europe and 

 introduced. 



V. RAPHANUS, Tourn. 



Annual or biennial herbs. Boot-leaves lyrate. Flowers in 

 long racemes, white or yellow, purple-veined. Sepals erect. 

 Pods rather long, slender-beaked, not splitting open but some- 

 times breaking across into 1-seeded joints. 



1. R. Raphanistrum, L. WILD RADISH, JOINTED CHARLOCK. 

 A stout, hairy annual 12 ft. high. Leaves cut into remote seg- 

 ments, which are coarsely toothed or serrate ; terminal segment 

 largest. Flowers yellow, turning whitish or purplish. Pods 

 necklace-shaped, with a long beak. A common weed eastward, 

 introduced from Europe. 



VI. NASTURTIUM, R. Br. 



Annual or biennial, mostly aquatic plants. Stems erect or 

 diffuse, often widely branching. Leaves simple, pinnately 

 lobed. Flowers small, white or yellow. Sepals spreading. 

 Stamens 1-6. Pod short and broad or nearly linear. Seeds 

 numerous in 2 rows in each cell.* 



1. N. officinale, R. Br. WATERCRESS. Aquatic herbs. Stems 

 smooth, diffuse, rooting at the joints. Leaves with 3-9 rounded, 

 pinnate lobes, the terminal lobe much the largest. Racemes 

 elongating in fruit. Petals white, twice the length of the sepals. 

 Pods linear, - ^ in. long, on slender, spreading pedicels. In ditches 

 and slow streams. Often used for salad.* 



2. N. palustre, DC. YELLOW WATERCRESS. Annual or bien- 

 nial. Stem erect, branched, slightly downy. Leaves irregularly 



