352 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



tained from the seeds of B. nigra and B. juncea. Most of the species 

 make palatable greens. 



Key to the species 



1. Beak half or more as long as the rest of the pod, flat or conspicuously angled, 



usually containing 1 seed in an indehiscent cell; leaves not clasping at 



base (2). 



2. Leaves petioled, pinnatifid; pedicels more than 5 (often 10) mm. long; 



pods ascending on spreading pedicels, the dehiscent part bristly, shorter 



than or equaling the beak 1. B. hirta. 



2. Leaves nearly sessile, the upper ones merely toothed; pedicels 3 to 5 mm. 



long; pods and pedicels strongly ascending, the dehiscent part of the 



pod usually smooth, longer than the beak 2. B. kaber. 



1. Beak usually less than half as long as the rest of the pod, conic, seedless (3). 



3. Upper leaves clasping, glaucous and glabrous, the lower ones usually with 



scattered hairs; pedicels spreading; pods 4 to 9 cm. long, stout, ascending, 

 with a stout beak forming one-eighth to one-third of the length of the 



pod 3. B. CAMPESTRIS. 



3. Upper leaves not clasping, not or only slightly glaucous, often sparsely 

 hirsute (3). 

 4. Pedicels in fruit less than 5 mm. long, erect; pods appressed to the stem, 

 1 to 2 cm. long, not more than 2 mm. in diameter, somewhat quad- 

 rangular 4. B. NIGRA. 



4. Pedicels in fruit more than 5 mm. long, spreading; pods not appressed to 

 the stem, 3 to 5.5 cm. long, 2 to 3.5 mm. in diameter, nearly terete 

 but the valves with a stout midnerve 5. B. juncea. 



1. Brassica hirta Moench, Meth. PI. Sup. 84. 1802. 



Sinapis alba L., Sp. PL 668. 1753. 



Brassica albaUobenh., Fl. Lusat. 1: 184. 1839. Not of Gilib., 

 1782. 



Base of the Mazatzal Mountains, Gila County, 4,000 feet (Collom 

 907). Adventive in the United States from Eurasia. 

 White mustard. 



2. Brassica kaber (DC.) L. C. Wheeler, Rhodora 40: 306. 1938. 



Sinapis arvensis L., Sp. PL 668. 1753. 

 Sinapis kaber DC., Regni Veg. Syst. 2: 617. 1821. 

 Brassica arvensis (L.) Rabenh., Fl. Lusat. 1: 184. 1839. 

 Not B. arvensis L. 1767. 



At roadside, Roosevelt, Gila County (Peebles et al. 5205), identi- 

 fication somewhat questionable. Widely distributed in the United 

 States; introduced from Europe. 



Charlock. 



3. Brassica campestris L., Sp. PL 666. 1753. 



Mesa (Maricopa County), Sacaton and south of Florence (Pinal 

 County) , occasional at roadsides, probably an escape from cultivation. 

 Native of Eurasia. 



Turnip. 



4. Brassica nigra (L.) Koch in Roelh., Deut. Fl. ed. 3, 4: 713. 1833. 



Sinapis nigra L., Sp. PL 668. 1753. 



Pinal, Maricopa, and Pima Counties, occasional at roadsides. 

 Widely distributed in the United States; naturalized from Europe. 

 Black mustard. 



