BRASSICACEAE 473 



mm. long : sepals oblong or nearly so, obtuse, 1 mm. long : petals yellow, about twice as 



long as the sepals : pods oblong, 6-14 mm. long, ascending or spreading. 



In damp places or on shaded banks, Iowa to Kansas, Tennessee, Florida and Texas. Spring and 

 summer. 



5. Roripa hispida (Desv.) Britton. Annual or biennial, with more or less densely 

 hirsute or hispid foliage. Leaves alternate ; blades oblong, elliptic, or oblanceolate in out- 

 line, 2-18 cm. long, pinnatifid or rarely only shallowly toothed, the lobes repand or toothed, 

 or the large terminal one again lobed : racemes elongating : pedicels 2-2.5 mm. long, finally 

 spreading : pods subglobose to oval, 2-3 ram. long, shorter than the pedicels. 



In damp soil, New Brunswick to British Columbia, Florida and New Mexico. Summer. 



6. Roripa palustris (L. ) Bess. Annual or biennial, glabrous or minutely pubescent. 

 Leaves alternate ; blades oblong, linear-oblong or oblanceolate, 2-20 cm. long, pinnatifid, 

 or the upper repand or coarsely toothed, the lower ones petioled and upper ones sessile or 

 nearly so, tlie lobes more or less deeply toothed : racemes elongating at maturity : pedicels 

 finally spreading, 2-6 mm. long : pods linear, or narrowly oblong, longer than the pedicels 

 or about equalling them in length, more or less strongly curved. 



In swampy soil, throughout North America, except the extreme north. Spring and summer. Also 

 in Europe. 



7. Roripa sphaerocarpa (A. Gray) Britton. Annual or perennial, glabrous. Stems 

 erect or decumbent and rooting at the lower nodes, 1-4 dm. long : leaves alternate, 3-8 

 cm. long ; blades thinnisli, tiie lower incised or lyrate-pinnatifid, the upper undulate or 

 shallowly toothed, all obtuse : pedicels slender, 2-6 mm. long, recurving : sepals oblong 

 or oblong-ovate, barely 1 nun. long : petals yellow, somewhat longer than the sepals : pods 

 subglobose, about 2 mm. in diameter, nodding. 



In low grounds, Illinois to Kansas, California and Texas. Summer. 



8. Roripa obtusa ( Xutt. ) Britton. Annual or biennial, glabrous. Stems 2-5 

 dm. long, nearly simple and erect or difl'usely branched : leaves alternate ; blades oblong 

 to oblanceolate, pinnatifid or pinnately-divided, 3-15 cm. long, petioled, the segments 

 angular, variously toothed or lobed, the terminal one largest : pedicels 1-3 mm. long, erect 

 or ascending : sepals about 1 mm. long : petals yellow, somewhat surpassing the sepals : 

 pods oblong, 4-8 mm. long, erect or ascending. 



In low grounds or on wet banks, Michigan to Vancouver Island and Texas. Spring and summer. 



9. Roripa sinuata (Nutt. ) A. S. Hitchcock. Perennial, pale green, glabrous or 

 nearly so. Stems procumbent or prostrate or sometimes decumbent, 2-6 dm. long, diffusely 

 branched : leaves numerous ; blades oblanceolate, oblong or lanceolate in outline, pinnatifid, 

 the segments nearly equal, entire or sparingly toothed : pedicels slender, spreading, 4-10 

 mm. long: sepals 2.5-3 mm. long: petals yellow, 4.5-6 mm. long: style slender: pods 

 linear to oblong, 6-10 mm. long, curved, acute at both ends. 



On banks, Saskatchewan to Minnesota, Arkansas, New Mexico and Oregon. Summer. 



10. Roripa sylv6stris (L. ) Bess. Perennial, glabrous. Stems ascending or decum- 

 bent, 2-7 cm. long, sometimes creeping at the base, more or less branched : leaves alternate, 

 4-15 cm. long ; blades often ovate or oblong in outline, pinnately divided, the segments 

 distant, entire or toothed : pedicels 4-10 mm. long, spreading : sepals oblong, 1-1.5 mm*, 

 long, obtuse : petals bright yellow : style short and thick : pods linear, nearly terete, 8- 

 15 mm. long. 



In waste places and moist soil, Massachusetts to Ohio, Virginia and Alabama. Summer to fall. 

 Naturalized from Europe. 



8. SISYMBRIUM L. 



Annual or biennial herbs, with erect branching stems. Leaves alternate, sometimes 

 mainly basal : blades entire, lobed or pinnatifid. Flowers perfect, in racemes. Sepals 4. 

 Corolla white, pink or yellow : petals 4, usually with claws. Stamens 6 : filaments unap- 

 pendaged. Ovary sessile : style short or wanting : stigma sometimes 2-lobed. Ovules 

 numerous. Pods elongated, nearly terete, often constricted between the seeds. Seeds in 

 1 row in each cavity, marginless. Cotyledons incumbent. Hedge Mustard. 



1. Sisymbrium officinale (L. ) Scop. Annual, glabrous or sparingly pubescent. 

 Stems 3-12 dm. tall, branched above, the branches widely spreading : leaves variable, 2-20 

 cm. long ; blades runcinate-pinnatifid, the segments 5-13, irregular, entire, toothed or 

 lobed, the terminal one largest ; petioles sometimes as long as the blades at the base of the 

 plant, decreasing in length above : pedicels 1-2 mm. long, erect or appressed : sepals ob- 

 long, 1.5-2 mm. long: petals yellow, spatulate, about twice as long as the sepals : pods 

 slender, 10-15 mm. long, each narrowed into a slender beak. 



In waste places, throughout cultivated North America. Naturalized from Europe. Spring to fall. 



