MUSTARD FAMILY 369 



spreading; anthers linear, curved and spirally coiled. Pods long-stipitate, 

 elongate-linear, terete; valves 1-nerved. Stigma sessile, small, simple. Seeds 

 in one row, oblong; cotyledons incumbent. 



Middle cauline leaves sessile by an auriculate base. 



Stem winged; petals greenish. 1. s. viridiflora 



Stem not winged; petals yellow. 2. S. confertiflora 



Middle cauline leaves petioled or sessile with a narrowed base. 



Plant white-villous. 3. S. tomentosa 



Plant not white-villous. 



Blades of the petals linear-oblong to elliptic, bright yellow. 



Blades of the petals one-third to two-thirds as long as the claws. 

 Pod arcuate, not tortuose. 

 Leaves sparingly hirsute. 



Filaments hairy; lower leaves pinnatifld, with lanceolate or oblone 



lobes. 4. S. pinnata. 



Filaments glabrous; lower leaves runcinate, with triangular lobes. 



5. S. runcinata. 



Leaves glabrous. 7. s. glauca 



Pod decidedly tortuose. 6. S. bipinnata. 



Blades of the petals as long as the claws. 

 Leaves glabrous. 



Leaves broadly lanceolate, the lower with short broad lobes; blades 



of the petals oblong; pod ascending. 8. S. integrifolia 



Leaves linear-lanceolate, usually all entire; blades of the petals broadly 



elliptic; pod recurved. 9. S. arcuata. 



Leaves finely puberulent. 10. S. canescens. 



Blades of the petals rounded-oval, ochroleucous. 11. S. albescens. 



1. S. viridiflora Nutt. Stem glabrous, 3-10 dm. high; basal and lower 

 cauline leaves glabrous or short-pubescent, 7-20 cm. long, oblanceolate or spatu- 

 late; petals 12-15 mm. long; claws subulate, about as broad as the linear blades; 

 filaments glabrous; stipe 5-8 mm. long; pod spreading, somewhat arcuate and 

 torulose, 4-5 cm. long. S. heterophylla Nutt. Bare hills: Wyo. Mont. Ore. 

 Nev. Submont. My-Jl. 



2. S. confertiflora (B. L. Robins.) Howell. Stem glabrous, terete, 4-6 dm. 

 high; basal leaves glabrous, 4-6 cm. long, oblanceolate; petals yellow, about 12 

 mm. long; claw about equalling the linear blades; pods 4-5 cm. long, ascending, 

 not torulose; stipe about 6 mm. long. Foot-hills: Ida. Ore. Submont. Ap-My. 



3. S. tomentosa Parry. Stem terete, woolly below, 8-15 dm. high, angled 

 above; lower leaves lyrately pinnatifid; terminal segment lanceolate, 3-7 cm. 

 long; lateral segments ovate-oblong; petals cream-colored; pedicels of the pod 

 equalling the stipe. Dry slopes: Wyo. Submont. 



4. S. pinnata (Pursh) Britton. Stem sparingly hairy or glabrate, 3-10 dm. 

 high, terete; leaves thick, commonly pinnatifid, with oblong or lanceolate divi- 

 sions, or the upper entire, more or less pubescent; petals 10-15 mm. long; pod 

 6-7 cm. long, spreading; stipe 10-15 mm. long, twice as long as the pedicels. 

 S. pinnatifida Nutt. Plains: S.D. Neb. Utah. Plain. My-Au. 



6. S. runcinata Rydb. Stem stout, glabrous; basal leaves about 2 dm. 

 long, lanceolate in outline, runcinately divided, softly pubescent, with long white 

 hairs; lobes broadly triangular or the lowest ones oblong; stem-leaves ovate to 

 oblanceolate, more glabrous; pods almost erect and straight, 6-7 cm. long, 1.5 

 mm. wide, on spreading pedicels about 1 cm. long. (?) S. rara A. Nels. Plains: 

 Ida. Son. 



6. S. bipinnata Greene. Stem flexuose, 2-6 dm. high, terete, glabrous; 

 leaves except the uppermost pinnatifid, with oblong or linear, often lobed divisions; 

 petals yellow, 8-10 mm. long; pod 4r-5 cm. long, torulose and tortuose; stipe 

 7-8 mm. long, about equalling the pedicels. Plains and dry draws: Wyo. 

 Colo. Kans. Plain. Jl-Au. 



7. S. glauca Rydb. Stem 4-6 dm. high, bluish green; lower leaves 1-1.5 

 dm. long, more or less pinnatifid, with linear-lanceolate or oblong lobes, the 

 terminal usually much longer than the rest; upper leaves usually entire, linear- 

 lanceolate; petals lemon-yellow, about 1 cm. long; claws pubescent; pedicels 

 about 1 cm. long, more or less spreading; stipes about 1.5 cm. long; pod proper 

 about 5 cm. long and 1.5 mm. thick, somewhat arcuate. Dry hills and table- 

 lands: Colo. N.D. Wyo. Plain Submont. 



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