MUSTARD FAMILY 



357 



Leaves not coarsely hirsute; perennials. 



Pubescence, if any, sparse and consisting of 2- 



forked or rarely 3-forked hairs. 

 IV. Drummondianae. 



SUFFRUTESCENTEa . 



Pubescence of at least the lower leaves decidedly stellate. 



V. MiCROPHYLLAE. 



Pods spreading or reflexed. 



Pods and calyx stellate. VI. Pulchr.^e. 



Pods not stellate. 



Pods 3-4 mm. wide. VII. 



Pods 1-2.5 mm. wide. 



Pods spreading or somewhat recurved on spreading pedicels. 



Pods only 1-1.5 mm. wide. VIII. Macounianae. 



Pods 1.5-2.5 mm. wide. 



Perennials, with a caudex. 



Plant tall, 3 dm. or more high, suffruticose at the base. 



IX. Pere.vn.\ntes . 

 Plant low, 1-2 dm. liigh, cespitose. X. Reconditae. 



Stout biennials or short-lived perennials, 3 dm. high or more. 



XI. Arcuatae. 

 Pods and pedicels reflexed. XII. Retrofractae. 



1. .4. lyrata. 



2. A. dmbigua. 



I. Lyratab. 



Pods about 0.75 mm. wide; style more than 0.5 mm. long. 

 Pods fully 1 mm. wide; style almost obsolete. 



II. FURCATAE. 



Seeds not winged; leaves hairy; pods 1 mm. wide or less. - 3. A. NuUallii. 



Seeds winged at the lower end; leaves merely ciliate on the margins; pods 1.5-2 mm. wide. 



4. A. furcata. 



III. HiRSUTAE. 



All sepals narrowly oblong; two of them with slightly saccate bases; petals 3-5 mm. long, 

 yellowish white, less than twice as long as the sepals. 5. A. ovata. 



Two of the sepals with strongly saccate bases, almost twice as broad as the others; petals 

 6-10 mm. long, pure white, fully twice as long as the sepals. 6. A. rupestris. 



IV. Drummondianae. 

 Stems 3 dm. high or more, solitary or 2 or 3 from the same root. 



Pods about 1.5 mm. wide. 7. A. Drummondii . 



Pods about 3 mm. broad. 8. A. connexa. 



Stems less than 3 dm. high, several from a cespitose caudex. 



Pods strictly erect, blunt. 9. A. albertina. 



Pods rather ascending, acute. 10. A. Lyallii. 



V. ]MlCROPHTl,LAE. 



stems more than 3 dm. high; basal leaves 3-10 cm. long. 11. A. oblanceolata . 



Stems usually less than 3 dm. high, from a branched caudex; basal leaves 1-2 cm. long. 

 Plant green; petals 7-8 mm. long; pods fully 2 mm. wide; stem-leaves ovate-lanceolate. 



12. A. oreophila. 

 Plant grayish; petals about 5 mm. long; pods 0.76-1.5 mm. wide; stem-leaves oblong 

 or linear, the lower oblanceolate. 

 Flowers few; pods more than 1 mm. wide; seeds somewhat 2-ranked; stem hirsute- 



ciliate below or glabrous. 13. A. microphylla . 



Flowers many; pods less than 1 mm. wide; seeds strictly in one row; stem finely 

 stellate. 14. A. Crandallii. 



VI. PULCHRAE. 



Seeds distinctly in two rows; stem-leaves not auricled. 



Petals purple, 8-10 mm. long. 15. A. pulchra. 



Petals white, 10-12 mm. long. 16. A. formosa. 



Seeds in one row; stem-leaves more or less auricled; petals 5-8 mm. long. 



Leaves usually coarsely toothed; petals pink, 6-8 mm. long. 17. A. subpinnatifida. 



Leaves entire; petals white, 5-6 mm. long. 18. A. MacDougalii. 



VII. SUFFRUTESCENTES. 



Stems suflfnitescent at the base; pods reflexed. 

 Stems not suffruticose; pods spreading. 



19. A. siiffriitescens. 



20. A. drepanoloba. 



I 



VIII. Macounianae. 



Petals about 4 mm. long; pod 3-4 cm. long; ba^al leaves 1-2 cm. long. 



21. A. Macounii. 

 Petals about 8 mm. long; pod 4-6 cm. long; basal leaves 4-6 cm. long. 



22. A. arcoidea. 



IX. Perennantes. 

 One species. 23. A. perennans. 



X. Reconditae. 



Leaves finely stellate. 



Leaves thick, canescent; stems simple. 



Pod about 1.5 mm. wide, acute. 24. A. Lemmonii. 



