476 BRASSICACEAE 



1. Erysimum cheiranthoides L. Minutely strigillose. Stems erect, 1-7 dm. tall, 

 simple or much branched : leaf-blades lanceolate to linear or rarely oblong, 2-10 cm. long,' 

 acute or obtuse at the apex, entire or repand-dentate, tapering at the base, the lower ones 

 with short petioles : racemes slender, elongating : pedicels 5-12 mm. long, ascending or 

 slightly reflexed : sepals oblong, 2 mm. long : petals yellow, twice as long as the sepals : 

 pods linear, 1-2 cm. long, glabrous, erect, ascending or spreading. 



In dry soil or on river banks, Newfoundland to Alaska, North Carolina and Tennessee. Summer. 

 WORMSEED MUSTARD. 



2, Erysimum Arkansanum Nutt. More or less densely scabrous and canescentwith 

 2 3-pronged hairs. Stems erect, 6-10 dm. tall, simple or branched : leaf-blades lanceolate, 

 linear or oblong, 3-15 cm. long, entire, repand or the lower ones sometimes pinnatifid : 

 pedicels spreading or ascending, stout, finally 5-10 mm. long : sepals linear-oblong, 10-12 

 mm. long, rather thin : petals orange-yellow ; blades suborbicular or obovate, 9-11 mm. 

 in diameter ; claws longer than the blades : pods elongated, spreading or ascending, 4- 

 sided, 8-10 cm. long, scabrous. 



In dry soil or on prairies, Ohio to Illinois and Texas. Spring. 



15. SINAPIS L. 



Annual or biennial caulescent herbs, with rough-pubescent foliage. Leaves alternate : 

 blades lobed or pinnatifid. Flowers perfect, in racemes or panicles. Sepals spreading. 

 Corolla mostly yellow, the 4 petals surpassing the sepals. Stamens 6 : filaments not 

 toothed. Ovary sessile : style persistent. Ovules numerous. Pods elongated, nearly 

 terete, constricted between the seeds, often hispid, each prolonged into a sword-like beak, 

 which sometimes contains one seed. Seeds thick or subglobose, marginless and wingless. 

 Cotyledons conduplicate. WHITE MUSTARD. 



1. Sinapis alba L. Pubescent with rigid spreading hairs. Stems 3-7 dm. tall, 

 branched : leaves variable, the basal with obovate pinnatifid blades and long petioles, the 

 upper stem-leaves with narrow, oblong to lanceolate, pinnatifid or coarsely-toothed blades 

 and shorter petioles, or those near the top of the stem sessile : pedicels ascending or spread- 

 ing, stout, 5-10 mm. long : sepals 4-5 mm. long : petals yellow, much longer than the 

 sepals : pods hispid, the body 8-15 mm. long, constricted below the seeds, the beak flat, as 

 long as the body or longer. 



In waste places, cultivated North America. Adventive from Europe and Asia. Summer. 

 i 



16. BRASSICA L. 



Annual biennial or perennial caulescent herbs, with glabrous glaucous or pubescent 

 foliage. Leaves alternate : blades lobed or pinnatifid, or the upper ones nearly entire. 

 Flowers perfect, in racemes. Sepals 4, sometimes equal at the base. Corollas bright yel- 

 low or white, the four petals manifestly clawed. Stamens 6 : filaments free, unappen- 

 daged. Ovary sessile : style persistent : stigma truncate or 2-lobed. Ovules numerous. 

 Pods elongated, terete or 4-angled, each prolonged into a conic indehiscent beak, the valves 

 1-3-nerved. Seeds in one row in each cavity, often subglobose, marginless. Cotyledons 

 conduplicate. 



Upper leaf-blades merely sessile. 



Pods erect or appressed, short-beaked, less than 2 cm. long : pedicels appressed. 1. B. nigra. 

 Pods more or less spreading, long-beaked, over 2 cm. long : pedicels not appressed. 



Stem glabrous, more or less glaucous : pedicels over 6 mm. long at maturity. 2. B.juncea. 



Stem hispid : pedicels less than 5 mm. long at maturity. 3. B. arvensis. 



Upper leaf-blades clasping. 4. B. campestris. 



1. Brassica nigra (L. ) Koch. Glabrous or sparingly pubescent. Stems 1-2 m. tall, 

 usually widely branched: leaves 5-20 cm. long ; blades more or less deeply lyrate-pinnatifid, 

 petioled, the segments 3-5, various, the terminal one largest, or the upper leaves sim- 

 ply toothed or entire, narrow : racemes slender : pedicels slender, 2-4 mm. long, erect : 

 sepals narrowly oblong, 4 mm. long : petals bright yellow, about twice as long as the sepals ; 

 blades broadened upward ; claws slender, longer than the blades : pods erect or appressed, 

 1-1.5 cm. long, somewhat constricted between the seeds, each abruptly constricted into a 

 slender beak. [Sinapis nigra L. ] 



In waste places and fields, southern British America and the United States. Naturalized from 

 Europe. Summer and fall. BLACK MUSTARD. 



