MUSTARD FAMILY 353 



dictyota Greene. Hills and plains: Hudson Bay Mich. Colo. Ore. Alaska- 

 Eurasia. Plain Mont. My-Jl. 



11. D. nitida Greene. Winter annual, often branched at the base; stems 

 1-3 dm. high, erect; basal leaves rosulate, oblanceolate, 1-3 cm. long, nearly 

 glabrous above, densely stellate beneath; stem-leaves oblong or lanceolate, 

 usually entire; petals yellow, about 2 mm. long; fruiting pedicels ascending, 

 6-15 mm. long; pod glabrous, erect, 8-15 mm. long, 2 mm. wide. D. stenoloba 

 S. Wats., not Ledeb. Mountains: Alta. Colo. Calif. B.C. Submont. Sub- 

 alp. 



12. D. Macouniana Rydb. Annual, almost scapose; stems ascending or 

 decumbent, less than 1 dm. high, glabrous and shining; basal leaves numerous, 

 broadly spatulate or obovate, 5-10 mm. long, finely stellate; stem-leaf usually 

 one, oval, obtuse, 5 mm. long; petals white, less than 3 mm. long; pod oblong- 

 linear, erect, about 1 cm. long and 2 mm. wide. Summits of the Rocky Moun- 

 tains: B.C. Submont. Subalp. Jl-Au. 



13. D. crassifolia Graham. Biennial or short-lived perennial; stems 2-10 

 cm. long, ascending, usually scapiform; basal leaves oblanceolate, 5-15 mm. 

 long; petals yellow, soon turning white, 2-2.5 mm. long; fruiting pedicels ascend- 

 ing, 4-7 mm. long; pod glabrous, 6-7 mm. long, 2 mm. wide. D. albertina Greene. 

 Alpine-arctic damp places: Greenl. 'Lab. Colo. 'Alaska. Subalp. Alp. Jl- 

 Au. 



14. D. Parryi Rydb. Annual, perfectly glabrous, except a few cilia on the 

 petioles; stems several, usually less than 1 dm. high, scapiform or rarely with 

 one stem-leaf; basal leaves numerous, linear or narrowly linear-oblanceolate, 

 1.5-2.5 cm. long; petals scarcely 2 mm. long, white or at first light yellow; pods 

 erect, oblong, 5-8 mm. long, 1.5-2 mm. wide. Alpine peaks: Colo. Wyo. 

 Subalp. Alp. Jl-Au. 



15. D. eurycarpa A. Gray. Densely cespitose; branches short and very 

 leafy; leaves oblanceolate, about 12 mm. long, densely stellate; scape scarcely 

 exceeding the leaves, few-flowered; pod oblong-ovate, acute, glabrous; style 2 

 mm. long: High mountains: Calif. Nev. Ida. Alp. Subalp. 



16. D. alpina L. Scapose perennial; leaves basal, rosulate, oblanceolate, 

 l-3*cm. long, nearly glabrous above, sparingly stellate beneath; scapes 5-15 cm. 

 long, stellate; petals yellow, spatulate, 5-7 mm. long; pod lance-oblong, 7-10 

 mm. long, 3 mm. wide. Arctic and alpine ridges: Greenl. Lab. B.C. Alaska; 

 arctic Eurasia. Alp. Je-Jl. 



17. D. glacialis Adams. Scapose perennial; leaves basal, rosulate, stellate 

 on both sides, 1-3 cm. long; scape 5-15 cm. high; petals yellow, 5-6 mm. long; 

 fruiting pedicels ascending; pod lance-oblong, 6-8 mm. long, 3 mm. wide D. 

 laevicapsula Payson. Alpine-arctic situations : Greenl. Wyo. Wash. Alaska; 

 Asia. Subalp. Alp. Je-Jl. 



18. D. argyrea Rydb. A cespitose tufted perennial, with underground 

 horizontal stems; basal leaves obovate, 3-7 mm. long, in dense rosettes, almost 

 silvery; petals yellow, 3 mm. long, obovate; pedicels in fruit 5-8 mm. long; pods 

 lanceolate, 6-7 mm. long, 2.5-3 mm. wide, minutely stellate. Crevices of rocks: 

 Ida. Subalp. Jl. 



19. D. incerta Payson. Cespitose, acaulescent, pulvinate perennial; 

 leaves basal, oblanceolate or linear-oblanceolate, 5-15 mm. long, firm, with a 

 strong midrib; petals yellow, obovate, emarginate, 4-5 mm. long; scapes 5-10 

 mm. long; fruiting pedicels ascending; pods lance-oblong, pubescent, 6-7 mm. 

 long, 2.5-3 mm. wide. Rocky mountain summits: Alta. Mont. Wyo. 

 Mont. Alj). 



20. D. densifolia Nutt. Densely pulvinate cespitose perennial; leaves 

 basal, rosulate, densely imbricate, less than 1 cm. long, with thick midrib, 

 stellate and hispid; scape 1-5 cm. long, villous; petals yellow, about 5 mm. 

 long; pedicels ascending; pod elliptic, 6-8 mm. long, 3-4 mm. wide, densely 

 stellate. D. Mulfordae Payson, typical form with elongate inflorescence and 



