FLOWERING PLANTS AND FERNS OF ARIZONA 403 



type of P. viscidvla from the Santa Rita Mountains {Pringle in 1881). 

 Southeastern Arizona, Chihuahua, California, and Baja California. 



20. Potentilla subviscosa Greene, Torre v Bot. Club Bui. 8: 97. 



1881. 



Coconino County, 6,500 to 12.000 feet, coniferous forests and 

 mountain meadows, May and June. New Mexico and Arizona. 



More widely distributed than the typical form in Arizona is var. 

 ramulosa (Rydb.) Kearney and Peebles (P. ramvlosa Rydb.), which 

 ranges in the mountains from Coconino to Pima County. It is dis- 

 tinguished by the less deeply and more coarsely incised leaflets, and 

 often by a less strictly acaulescent habit of growth. The type of P. 

 ramulosa was collected in Arizona (Lemmon 399). 



21. Potentilla albiflora L. Williams, Torrev Bot. Club Bui. 61: 260. 



1934. 

 Known only from the Pinaleno Mountains, Graham County 

 (Goodding 1045 the type collection. Kearney and Peebles 9794, etc. . 

 7,500 to 9.500 feet, abundant on rocky slopes and in open coniferous 

 forests, May to August. 



The petals were described by Williams as white but the}' are pale 

 yellow when fresh. 



12. PURPUSIA 



Plants small, herbaceous, perennial, glandular-pubescent; stems 

 from a branched caudex; basal leaves pinnate with 5 to 11 leaflets, 

 these broad, deeply toothed or cleft; flowers few, in loose cymose 

 panicles; hypanthium campanulate or turbinate, without bractlets; 

 petals small, yellow or whitish; stamens 5, inserted on the margin of 

 the hypanthium remote from the pistils; pistils several (up to 11), 

 borne on an elongate, conic or cylindric, stalked, hairy receptacle; 

 achenes longitudinally ribbed (in the Arizona species). 



1. Purpusia arizonica Eastw., Madrono 2: 12. 1930. 



Purpusia osterhoutii A. Nels., Amer. Jour. Bot. 21: 574. 1934. 



Known only from the Grand Canyon, both rims, 6.500 to 7,500 

 feet, crevices of rocks, June to August. 



P. osterhoutii (type Osterhout 7103) was described as having a 

 glabrous receptacle, but in other characters the description corre- 

 sponds closely with that of P. arizonica. 



13. GEUM. Avexs 



Plants herbaceous, perennial; flowering stems from a thick root- 

 stock or caudex, leafy or subscapose: leaves pinnate or deeply pinna- 

 tifid; flowers solitary or in few-flowered cymes, relatively large: 

 petals yellow, sometimes tinged with purple or pink; stamens and 

 pistils numerous; achenes tipped by the long, often plumose, some- 

 times jointed, persistent styles. 



Key to the species 



1. Stems leafy, the lower stem leaves not much smaller than the basal ones; 

 leaves with few divisions, the terminal one much the largest; styles con- 

 spicuously geniculate above the middle, the upper section promptly 

 deciduous, the persistent lower section becoming sharply hooked (2). 

 2. Upper section of the style hirsute, the lower section glabrous or sparsely 

 pubescent toward the base, not glandular 1. G. strictum. 



