MUSTARD FAMILY 335 



Annuals or biennials. 



Pods thickened towards the apex and truncate, curved, longer than the pedicels. 



5. R. clavata. 

 Pods not thickened towards the apex, acute or obtuse. 



Pods spherical to oblong-ellipsoid, in the latter case shorter than the pedicels. 

 Pedicels 4-10 mm. long. 



Pods 5-8 mm. long, 2-3 mm. thick; stem sparingly hirsute. 



6. R. pacifica. 

 Pods 3-5 mm. long (rarely 6-7 mm. in R. palustris), 1.5-2 mm. thick. 



Stem more or less hirsute. 7. R. hispida. 



Stem glabrous. 



Stem tall, 3-8 dm. high; stigma prominent, 2-lobed. 



8. R. terrestris. 

 Stem low, divaricately branched, 1-3 dm. high; stigma scarcely 



thicker than the style. 9. R. alpina. 



Pedicels 2-5 mm. long, pod globose. 10. R. sphaerocarpa. 



Pods oblong to linear-cylindrical, equalling or longer than the short pedicels. 

 Style about 1 mm. long. 



Leaves nearly all pinnatifid, with obtuse divisions. 11. R. obtusa. 

 Leaves mostly sinuate, or if pinnatifid, with acute divisions. 



Pods short-ellipsoid, straight on straight pedicels. 10. R. sphaerocarpa. 

 Pods elongate-ovoid, curved, on curved pedicels. 12. R. curvipes. 

 Style minute, 0.5 mm. long or less. 



Pods 1.5 mm. thick or less, distinctly pedicelled; seeds tuberculate. 



Petals about 2 mm. long or more; pods linear, 1 mm. or less thick, 



strongly curved. 

 Leaves divided to near the midrib, their segments obtuse. 



13. R. curvisiliqua. 



Leaves merely cleft, with acute segments. 14. R. Nuttallii. 



Petals rarely more than 1 mm. long; pods usually slightly tapering 



upwards, about 1.5 mm. thick, straight or slightly curved. 

 Leaves pinnatifid. 



Low, slender, less than 2 dm. high; leaves not auricled at the base. 



15. R. lyrata. 



Taller and stouter, over 2 dm. high; petioles of the stem-leaves 

 auricled at the base. 16. .R. Underwoodii. 



Leaves entire or merely sinuate. 17. R. Integra. 



Pods fully 2 mm. thick, almost sessile; seeds pitted. 18. R. sessiliflora. 



1. R. calycina (Engelm.) Greene. Stem hirsute, erect, 2-3 dm. high; leaves 

 oblong or oblanceolate, sessile and even subclasping, coarsely toothed; racemes 

 rather dense; pedicels ascending, 5-8 mm. long; petals light yellow, slightly 

 exceeding the sepals; pod erect, ovate, 3-5 mm. long; style more than half as 

 long. Nasturtium calycinum Engelm. Sandy bottoms: Mont. Plain. Jl. 



2. R. trachycarpa (A. Gray) Rydb. Stem branching, papillose-puberulent 

 or glabrous; leaves lyrate-pinnatifid, with many oblong divisions, nearly gla- 

 brous; petals white, 5 mm. long; pedicels spreading; pod oblong-linear, curved, 

 ascending. N '. trachycarpum A. Gray. Wet places: s Colo. Plain Submont. 

 Je. 



3. R. Columbiae (Suksd.) Greene. Stem branched, 1-3 dm. high, papil- 

 lose or glabrate; leaves pinnatifid, with many oblong often toothed divisions; 

 petals yellow, spatulate, 4 mm. long; pedicels ascending or spreading; pod ascend- 

 ing or erect, curved, 5-8 mm. long; style nearly 2 mm. long. Roripa calycina 

 Rydb., not Nasturtium calycinum Engelm. River banks and wet sandy places: 

 Mont. Neb. N.M. Wash. Plain Submont. Je-Jl. 



4. R. sinuata (Nutt.) Greene. Stems 1^4 dm. high, glabrous or nearly so; 

 leaves glabrous, pinnately divided or cleft, with numerous oblong or lanceolate, 

 often toothed divisions; petals yellow, 4-5 mm. long; pod curved up wards, ^gla- 

 brous, 1-1.5 cm. long, 2 mm. thick; style 3 mm. long. N. sinuatum Nutt. 

 River valleys : Sask. Minn. 111. Tex. Ariz. Wash.; Ont. Plain. Ap-Au. 



5. R. clavata (Rydb.) J. M. Macoun. Biennial, perfectly glabrous; stem 

 6-10 dm. high, simple up to the inflorescence; leaves lyrate-pinnatifid, 5-10 cm. 

 long, more or less auricled at the base; lobes oblong to ovate, broadly dentate; 

 pedicels in fruit 5-10 mm. long, divaricate; petals spatulate, about 3 mm. long; 

 pod 10-12 mm. long, 2.5-3 mm. thick; style nearly 1 mm. long. Roripa clavata 

 Rydb. River valleys: Ida. Ore. 'Alaska. Submont. Ap-S. 



6. R. pacifica (Howell) Greene. Annual or biennial; stem 3-10 dm. high, 

 glabrous, or slightly hairy, branching above; leaves lyrately pinnatifid or pin- 

 nately lobed, with oblong-lanceolate or triangular, toothed divisions; petals 



