OF ARTS AND SCIENCES : MAY 13, 1873. 561 



to the middle of the ovary. — New England, and from the Great 

 Lakes northward to Greenland, the Arctic Circle, and Alaska. 



27. P. Thurberi, Gray. Stems ascending, slender, 2° high ; pu- 

 bescence subvillous or minute ; stipules ovate, incisely toothed ; leaves 

 digitate ; leaflets 5-7, obovate to oblong, 2' long, obtuse, nearly 

 glabrous, coarsely serrate ; flowers dark purple, in an open cyme ; 

 calyx large, the bractlets equalling the sepals ; petals B" long, very 

 broadly obcordate, equalling the calyx ; disk thickened, pentagonal, 

 bearing at the angles opposite to the sepals the 5 inner stamens with 

 stout fleshy filaments, the 15 outer stamens with slender filaments 

 arising from the margin of the base of the calyx ; carpels numerous, 

 sessile on the short hairy receptacle ; style terminal. — New Mexico. 



28. P. biflora, Willd. Dwarf, csespitose, the ascending stems 

 slender, 2-3' high ; pubescence villous, the pedicels subtomentose ; 

 leaves all radical, ternate ; the middle leaflet petiolulate and 3-parted, 

 the lateral 2-parted, the linear segments 3 — 6" long with strongly revo- 

 lute margins and villous-tufted, becoming nearly glabrous above ; flow- 

 ers 1-5, yellow; bractlets broad, equalling the acute sepals; petals 

 cuneate-obcordate, 2\" long, exceeding the calyx ; disk glandular 

 between the five inner stamens, lobed ; filaments all subfiliform ; car- 

 pels 15 - 30, short-pedicelled, the pedicels and small receptacle villous 

 with long hairs ; style attached below the apex of the ovary. — On 

 the Arctic Coast and in Siberia. No American specimens found in our 

 collections. 



* * * Style attached below the middle of the ovary ; carpels on 

 short pedicels, and, with the receptacle, densely Villous ; disk not 

 thickened ; more or less woody perennials. 



29. P. fruticosa, L. Shrubby, much branched, 1-4° high ; 

 pubescence silky-villous ; stipules scarious ; leaves pinnate ; leaflets 

 5- 7, crowded, oblong-lanceolate, 2-12" long, entire, usually whiter 

 beneath and the margins revolute ; flowers on slender pedicels in 

 rather loose cymes or solitary ; bractlets equalling the acute sepals ; 

 petals yellow, orbicular, 2 - 6" long, exceeding the calyx ; stamens 30 ; 

 carpels 20. — From New Jersey to Labrador and Wisconsin, and 

 northward to the Arctic Circle and Behring Strait, and in the moun- 

 tains to Colorado, Nevada, and Northern California. 



Var. parvifolia. An alpine form, with minute densely silky 



VOL. VIII. 71 



