562 PROCEEDINGS OF THE AMERICAN ACADEMY 



leaves, 2" long, and small flowers. — E. Humboldt Mts., Nevada, and 

 in the Wahsatch. 



30. P. tridentata, Soland. Caudex woody, creeping, branched and 

 tufted, the ascending herbaceous stems 1 - 10' high, subnaked - r pubes- 

 cence sparse, silky, appressed ; stipules lanceolate, entire ; leaves 

 ternate ; leaflets subcoriaceous and shining above, cuneate-oblong, i-P 

 long, 3 - 5-toothed at the truncate apex ; flowers white, loosely cymose ; 

 bractlets nearly equalling the sepals, smoother ; petals obovate-oblong, 

 2 - 3" long, exceeding the calyx ; stamens and carpels 20, the achenia 

 becoming sparingly villous. — Higher peaks of the Alleghanies and 

 White Mts. ; coast of Massachusetts ; Labrador ; Greeenland ; and 

 from the Great Lakes to lat. 64°. P. return, Miiller {Fl. Dan. 5, 

 t. 799), is the older name by several years, but is less appropriate. 



III. Style filiform, attached to the middle of the ovary or below the 

 apex ; peduncles axillary, solitary, 1-flowered ; carpels glabrous, 

 short-pedicelled, the pedicel and receptacle very villous ; herba- 

 ceous perennials with mostly creeping or decumbent stems; flow- 

 ers yellow. 



31. P. Anserina, L. Spreading by slender many-jointed ruuners, 

 white-tomeutose and silky-villous; stipules many-cleft; leaves all radi- 

 cal, pinnate ; leaflets 7 - 21, with smaller ones interposed, oblong, 

 sharply serrate, silky-tomentose at least beneath ; bractlets often 

 incisely cleft, about equalling the sepals ; petals oblong, broadly ellipti- 

 cal and entire or obcordate, 3 - 6" long, exceeding the calyx ; stamens 

 20, rarely 25 ; carpels 20 - 40 ; style attached to the middle of the 

 ovary. — Pennsylvania to Illinois, New Mexico and California, and 

 northward to the Arctic Ocean and Greenland. Very variable in size 

 and pubescence, from the wholly glabrous minute plant of Greenland 

 to the ordinary form with leaflets nearly or quite glabrous above or 

 equally silvery-silky on both sides, and the still larger western form 

 with leaves often 1-2° lonj;. 



32. P. Canadensis, L. Stems slender and decumbent or prostrate ; 

 pubescence villous, often scanty ; stipules mostly entire ; leaves ternate, 

 the lateral leaflets parted nearly to the base, cuneate-oblong or -obovate, 

 incisely serrate, nearly glabrous above ; peduncles exceeding the 

 leaves ; bractlets longer than the sepals, entire ; petals broadly obovate 

 or obcordate, 2 - 3" long ; stamens 20 ; carpels 20 - 40 ; style attached 



