254 ROSACE AE (ROSE FAMILY) 



cyme extending well down the stem: calyx densely glandular- viscid ; bractlets 

 linear to ovate, shorter than the long-acuminate sepals: petals orbicular, 

 much longer than the sepals. Rocky canons and slopes; throughout the Rocky 

 Mountains. 



6. Drymocallis glutinosa (Nutt.) Rydb. 1. c. 196. Viscid with long glandular- 

 villous hairs: stem stout, branched above, 4-8 dm. high: leaflets 7-11, coarsely 

 incised-serrate, pubescent or glabrate, 3-6 cm. long; the terminal one obovate; 

 the lateral obliquely elliptic or suborbicular: cyme broad with divergent 

 branches, in fruit somewhat flat-topped: flowers about 2 cm. broad, yellow: 

 calyx viscid-villous, the acuminate sepals distinctly exceeding the bractlets 

 and much shorter than the elliptic or orbicular petals. Montana and Wy- 

 oming to California. 



21. ARGENTINA Lam. SILVERWEED 



Perennial herbs, with interruptedly pinnate leaves and long runners. 

 Flowers yellow, solitary on long peduncles from the axils of the basal leaves. 

 Petals suborbicular. Stamens 20-25. Style filiform, attached near the middle 

 of the ovary; carpels glabrous; the receptacle very villous. Potentilla in part. 



Leaves silvery silky-tomentose below, green above . . . . 1. A. anserina. 



Leaves silvery silky- villous on both sides 2. A. argentea. 



1. Argentina anserina (L.) Rydb. Mem. Dept. Bot. Columbia Univ. 2: 159. 

 1898. Spreading by slender many-jointed silky-tomentose runners: leaves 

 all radical; stipules many-cleft; leaflets 7-21, with smaller ones interposed, 

 oblong, sharply serrate, green and glabrate above, white silky-tomentose 

 beneath. Potentilla anserina L. Common; in the mountain districts from 

 Mexico northward to the arctic seas; also in Europe and Asia. 



2. Argentina argentea Rydb. Bull. Torr. Bot. Club 33: 143. 1906. Sim- 

 ilar but more robust, the runners shorter and stouter, somewhat enlarged at 

 the nodes, which are sheathed by the large conspicuous many-cleft stipules, 

 silvery-silky as are also the peduncles: leaves suberect, larger, densely silvery 

 silky-villous on both sides, but not tomentose"; leaflets 15-29, elliptic to 

 obovate. Infrequent; in the mountain districts from New Mexico to the 

 far north. 



22. HORKELIA Cham. & Schlecht. 



Herbaceous perennials, with pinnate leaflets and flowers in cymes or open 

 panicles. Leaflets usually numerous, often imbricated. Sepals and bractlets 

 5. Petals 5, white or yellow. Stamens 5-20, inserted in the throat of the 

 rather deep calyx-tube. Style filiform, inserted near the base of the ovaries; 

 carpels (in ours) few. 



I. Horkelia Gordonii Hook. Journ. Bot. & Kew Card. Misc. 5: 341. 1853. 

 Caudex thick, resinous, and scaly: stem scapose, 1 or 2-bracted, minutely 

 glandular-puberulent or glabrous, 1-2 dm. high: leaves puberulent or gla- 

 brate; leaflets in 10-20 approximate pairs, divided into 3-5 oblong or linear 

 segments: cyme capitate: calyx glandular-pubescent, yellowish; bractlets lin- 

 ear, half as long as the sepals: petals yellow, spatulate, shorter than the sepals: 

 stamens 5. Ivesia Gordonii T. & G. Subalpine; Central Wyoming to Cali- 

 fornia. 



23. POTENTILLA L. CINQUEFOIL 



Herbs or shrubs with alternate stipulate digitately or pinnately compound 

 leaves and mostly yellowish cymose (or solitary) flowers. Calyx persistent, 

 with 5 sepals and 5 alternating bractlets. Petals 5, mostly obovate-emarginate. 

 Stamens 10-30, with small anthers. Carpels usually numerous, mostly in 

 3 series, inserted on a dry, usually hairy receptacle; style terminal, deciduous. 

 Achenes (in ours) glabrous. 



