WOOTON AND STANDLEY FLORA OF NEW MEXICO. 



311 



KEY TO THE SPECIES. 



Annuals or biennials with very leafy many-flowered cymes. 



Achenes with a corky gibbosity on the upper suture; leaves 



pinnate, with 4 or 5 pairs of leaflets 1. P. paradoxa. 



Achenes not gibbous; leaves pinnate or digitate. 



Lower leaves pinnate, with 2 approximate pairs of 



leaflets 2. P. rivalis. 



Leaves all digitate. 



Petals about half as long as the sepals; achenes 

 smooth; hypanthium in fruit 5 mm. wide or 



less; stamens 10 3. P. millegrana. 



Petals equaling the sepals or nearly so; achenes 

 rugulose; hypanthium about 7 mm. wide; 



stamens 15 to 20 4. P. monspeliensis. 



Perennials with few-flowered, not very leafy cymes. 

 Flowers red. 



Leaves green above, white-tomentose beneath 5. P. atrorubens. 



Leaves glabrate or silky beneath, without tomentum 6. P. thitrberi. 



Flowers yellow. 



Leaves digitate. 



Plants glabrous throughout; 7. P. sierrae-blancae . 



Plants abundantly pubescent. 



Plants tall, more than 20 cm. high 11. P. filipes. 



Plants low, less than 20 cm., usually less than 

 10 cm. high. 



Leaves tomentose beneath 10. P. bicrenata. 



Leaves not tomentose beneath. 



Stems simple, erect; sepals and bract- 

 lets not incurved 8. P. diver sifolia. 



Stems much branched, spreading; 



sepals and bractlets incurved. . . 9. P. subviscosa. 

 Leaves odd-pinnate. 



Style not longer than the mature achene, thickened 

 at the base; leaflets deeply lobed into narrow 



oblong teeth 12. P. strigosa. 



Style much longer thau the mature achene, filiform; 

 leaflets not lobed, merely coarsely toothed or 

 nearly entire. 

 Leaves green on both sides, or merely strigose. 



Pedicels arcuate-spreading in fruit 19. P. plattensis. 



Pedicels erect. 



Stems stout, 00 to 70 cm. high; leaflets 



obovate-oblong, coarsely serrate. 13. P. ambigens. 



Stems 10 to -10 cm. high, slender; 



leaflets cuneate or linear-oblong, 



toothed only at the apex. 



Stems ascending or decumbent; 



Leaflets conduplicate; pistils 



numerous 14. P. crinita. 



Stems erect; Leaves Hat; pistils 5 



to 12 15. P. lemmoni. 



Leaves tomentose beneath. 



Leaves almost equally white pubescent on 



both Burfa< ee L6. /'. kippiana. 



