FLOWERING PLAXTS AXD FERXS OF ARIZOXA 339 



13. Seeds flat: herbage densely stellate-pubescent or lepidote; leaf 

 blades entire or nearly so (the basal ones lyrate in one specif- ; 

 dry-land plants 24. Lesquerella. 



10. Capsules more than twice as long as wide 14 . 



14. Sepals in anthesis divaricate or reflexed; anthers soon becoming sharply 

 curved or coiled, sagittate: stigma entire or very nearly so: leaf 

 blades, at least the lower ones, usually coarsely toothed, cleft, or 

 pinnatifid: blades of the petals narrow, flat or nearly so: pods 

 elongate, slender, terete or subterete, commonly stipitate (15 . 

 15. Petals yellow or ochroleucous, 8 mm. long or longer: pods spreading 

 or decurved, slender but not filiform, the stipe at least 10 mm. long. 



1. Stanley a. 



15. Petals white or pinkish, 5 to 7 mm. long: pods spreading or curved 



upward, almost filiform, the stipe seldom more than 3 mm. long, 



sometimes almost none 8. Staxleyella 



14. Sepals in anthesis erect or ascending (16). 



16. Calyx closed or nearly so in anthesis, usually somewhat flask-shaped, 



the sepals spreading, if at all, only at the tip: herbage glabrous or 



nearly so, commonly more or less glaucous: anthers sagittate; 



pods elongate (17). 



17. Petals violet purple, 10 to 15 mm. long, the blades flat or nearly 



so, much wider than the claw.-: anthers soon becoming strongly 



curved or coiled: stigma entire or slightly 2-lobed, with lobes 



parallel to the placentas and septum 12. Sisymbrium. 



17. Petals not violet purple, the blades strongly crisped, channeled, 



or cucullate, little if any wider than the claws; anthers straight 



or moderately curved: stigma entire or, if 2-lobed, then with 



lobes at a right angle to the placentas and septum, hence over 



the valves: pods sessile or very nearly so (18). 



IS. Valves of the mature pods remaining attached to the frame 



(replum) toward the apex; stem leaves not clasping; flowers 



inconspicuous: pods conspicuously beaked, becoming reflexed, 



somewhat compressed, less than 2 mm. wide: seeds 



winged 7. Streptaxthella, 



18. Valves of the mature pods separating completely from the 



frame (19). 



19. Pods at maturity terete or nearly so (immature pods of C. 



cooperi appearing flat in dried specimens), about 2 mm. 



wide: seeds not or scarcely winged; stem leaves various: 



petals brown purple or ochroleucous 6. Caulaxthus. 



19. Pods at maturity strongly compressed, 3 mm. wide or wider 

 (or, if narrower, then the inflorescence bracteate, diffusely 

 paniculate): seeds flat, conspicuously winged: stem leaves 

 clasping, cordate, or sagittate at base: petals (at least the 



veins) brown purple 9. Streptanthus. 



16. Calyx open in anthesis, not flask-shaped: petals not strongly crisped, 

 channeled, or cucullate, or sometimes moderately so in Sisym- 

 brium and Thelypodium (20 . 

 20. Mature pods strongly compressed parallel to the partition, flat or 

 twisted, or, if subterete (in Arabis glabra), then erect, crowded, 

 and not more than 1 mm. wide: pubescence, if any. usually at 

 least partly of stellate or forked hairs (21). 

 21. Pods not more than 12 mm. long, often twisted: petals white or 

 yellow 28. Drab a. 



21. Pods much more than 12 mm. long, not twisted; petals white, 



ochroleucous, or purplish pink 32. Arabis. 



20. Mature pods terete or tetragonal, not strongly compressed 

 (except in Diplotaxis) but sometimes appearing so in immature 

 dried specimens (22). 



22. Pods becoming strongly reflexed (23). 



23. Pubescence partly of forked hairs; stem leaves entire or 

 merely dentate: sepals and petals purple. 



5. Lamprophragma. 



23. Pubescence of simple hairs only: stem leaves pinnately cleft: 

 sepals greenish; petals whitish. _ 14. Microsisymbbium. 



