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 em. 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 mm. 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, the 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. 
oe In swampy soil, throughout North America, except the extreme north. Springandsummer. 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 
em. long ; blades thinnish, the 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 mm. 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 (Nutt.) Britton. Annual or biennial, glabrous. Stems 2-5 
dm. long, nearly simple and erect or diffusely 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 sylvéstris (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 : se variable, 2-20 
em. 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 
lant, decreasing in length above: pedicels 1-2 mm. long, erect or appressed : sepals ob- 
ong, 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. 
