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 haK 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 haii-y. Lower leaves lyrate with the terminal lobe m.uch 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, Toum. 



Annual or biennial herbs. Root-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. Kaphanistrum, L. Wild Radish, Jointed Charlock. 

 A stout, hairy annual 1-2 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. NASTURTIXJM, R. Br. 



. Annual or biennial, mostly aquatic plants. Stems erect or 

 diffuse, often widely branching. Leaves simple, pinnately 

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

 Stamens 1-6. Pod short and broad gr 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. Ybllow^ Watercress. Annual or bien- 

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



