484 BRASSICACEAE 



2. Arabis petiolaris A. Gray. Annual or biennial, glabrous, or sparingly pubescent 

 with reflexed simple hairs. Stems erect, 4-9 dm. tall, simple or branched above : basal 

 leaves few, 12-20 cm. long, with somewhat lyrate-pinnatifid blades ; segments 5-7, sinuate : 

 stem-leaves various ; blades all petioled, lower ones pinnatitid or hastately lobed, upper 

 entire or merely sinuate : jiedicels becoming 6-10 mm. long : petals purpli,sh : pods as- 

 cending, 5-7.5 cm. long, 3-4 mm. broad, slender-beaked, the valves 1-nerved below the 

 middle : seeds broadly winged. 



On plains or prairies, Texas, mainly between tlie Colorado River and the Rio Grande. Spring. 



3. Arabis lyrata L. Biennial or perennial, glabrous, or jni'Descent near the base. 

 Stems solitary or tufted, erect or ascending, 1-4 dm. tall, often diftusely branched : basal 

 leaves 1-4 cm. long, with short margined petioles ; blades spatulate or oblanceolate in 

 outline, lyrate-pinnatifid : stem-leaves 1-3 cm. long, linear and entire or some of the 

 lower ones bi'oader and irregularly toothed : pedicels ascending, 5-10 mm. long : sepals 

 oblong, 2-2.5 mm. long, obtuse : petals white, twice or thrice as long as the sepals : pods 

 narrowly linear, 2-3 cm. long, ascending, straiglit or slightly curved : seeds in 1 row, wingless. 



On cliffs and in sandy soil, Ontario to Manitoba, North Carolina and Missouri. Spring. 



4. Arabis dentata T. & G. Biennial, pubescent with fine rigid stellate hairs. 

 Stems erect, 2-6 dm. tall, branching from the base, the branches ascending or decumbent : 

 basal leaves spatulate, 5-12 cm. long ; petioles winged, shorter than the remotely dentate 

 blades : stem-leaves quite numerous ; blades sessile, clasping, more finely toothed than the 

 basal, usually oblanceolate to oblong : pedicels 1-3 mm. long, finally spreading : sepals 

 oblong, 1.5 mm. long, obtuse: petals white, nearly twice as long as the sepals: pods 

 linear, 2-2.5 cm. long, straight, spreading : seeds in 1 row, marginless. 



In moist soil, New York to Minnesota, Virginia (?), Tennessee and Missouri. Spring. 



5. Arabis patens Sulliv. Biennial, more or less densely hirsute with simple or 

 branched hairs, or rarely glabrous above. Stems solitary or loosely tufted, 3-7 dm. tall, 

 simple or sometimes sparingly branched : basal leaves 3-10 cm. long ; blades oblanceolate, 

 spatulate or obovate, on winged petioles : stem-leaves shorter than the basal ; blades oblan- 

 ceolate or obovate to ovate or lanceolate, sessile, serrate or dentate like the basal, but the 

 teeth usually more prominent : pedicels finally spreading, 1-2.5 cm. long : sepals oblong, 

 4-5 mm. long, obtuse, scarious-margined : petals white, twice as long as the sepals : pods 

 narrowly linear, spreading or erect-spreading, 2.5-4 cm. long : seeds in 1 row, narrowly 

 winged. 



On river banks, Pennsylvania to Minnesota, Alabama and Missouri. Spring and summer. 



6. Arabis hirsiita (L. ) Scop. Biennial, finely hirsute throughout with simjile or 

 forking hairs. Stems erect, 2-9 dm. tall, simple or nearly so, sometimes branched at the 

 base : basal leaves 2-4 cm. long, with short winged petioles, and obovate, elliptic or spat- 

 ulate repand or shallowly dentate blades : stem-leaves 1-6 cm. long ; blades sessile, clasp- 

 ing by tlie auricled bases, oblong to lanceolate, or rarely linear, nearly entire, or dentate : 

 pedicels erect or nearly so, finally 4-12 mm. long : sepals oblong, 2.5-3 mm. long, obtuse : 

 petals greenish white, or nearly white, about twice as long as the sepals : pods narrowly 

 linear, 2.5-3 cm. long, erect or appressed : seeds in one row, narrowly margined. 



In rocky or poor soil, Newfoundland to British Columbia, Georgia and California. Also in Europe 

 and Asia. Spring to fall. 



7. Arabis laevigata (Mulil.) Poir. Biennial, glaucous. Stems ei-ect, 3-10 dm. tall, 

 simple, or virgately branched above : basal leaves with varying petioles and spatulate or 

 obovate dentate blades : stem-leaves 3-15 cm. long ; blades oblong, lanceolate or linear, 

 entire or coarsely toothed, sessile, clasping by the strongly auricled bases : pedicels ascend- 

 ing, finally spreading, 8-10 mm. long : sepals narrowly oblong, about 5 mm. long, obtuse : 

 petals white or greenish white, about twice as long as the sepals : pods narrowly linear, 

 6-10 cm. long, partially drooping : seeds in 1 row, broadly winged. 



In rocky soil, Quebec to Minnesota, Georgia and Arkansas. Spring. 



8. Arabis Canadensis L. Annual or biennial, more or less pubescent. Stems erect, 

 2-9 dm. tail, simple, or virgately branched above : basal or lower leaves with short petioles 

 and toothed or lyrate-pinnatifid blades : upper stem-leaves 3-12 cm. long ; blades tlun, 

 lanceolate or oblanceolate, nearly entire or shallowly toothed, acute : pedicels spreading 

 or recurved at maturity, 5-12 mm. long : sepals oblong, 4 mm. long, obtuse : petals 

 greenish white, about twice as long as the sepals : pods scythe-shaped, narrowly linear, 

 5-7 cm. long, drooping : seeds in 1 row, winged. 



In rocky woods, Ontario to Minnesota, middle Georgia and Texas. Spring and summer. 



24. SOPHIA Adans. 

 Annual or perennial caulescent herbs or shrubby plants, more or less densely pubescent 

 with short branched hair.s. Leaves alternate : blades 2-pinnatifid, or finely dissected. 



