ROSACEAE. 139 



stipules ovate, toothed, 1-2 cm. long; flowers yellow, about 1 cm. broad, 

 several in a loose cyme; petals obovate, longer than the reflexed acute calyx- 

 lobes; fruiting head globose, 1.5 cm. long; akenes hispid; styles jointed and 

 twisted near the tip, glabrous. In moist places in open woods. 



197. SIEVERSIA. 



Low perennial herbs with simple stems; radical leaves pinnate; 

 flowers in terminal cymes; sepals 5, erect or spreading, with 5 

 bractlets; petals 5; carpels sessile; styles not jointed, persistent, 

 erect, plumose or naked. 



Sieversia ciliata (Pursh) G. Don. Erect, from stout rootstocks, 30-50 

 cm. high, soft-hairy throughout; radical leaves tufted, oblanceolate in outline, 

 10-15 cm. long, pinnate with numerous leaflets, these cuneate, obovate, in- 

 cisely cleft into acute narrow lobes; cauline leaves 1 or 2, much reduced; 

 flowers long-peduncled, 3-5 in a cyme; calyx purplish, the linear bractlets 

 exceeding the triangular acute calyx-lobes; petals oblong, erect, yellowish or 

 purplish, shorter than the calyx; akenes with straight plumose tails, 2-3 cm. 

 long. Common on grassy hillsides. 



198. POTENTILLA. 



Annual or perennial herbs; leaves alternate, pinnate or pal- 

 mate, with stipules; flowers perfect, solitary or in cymes; sepals 

 5, rarely 4, with 5, rarely 4, alternate bractlets; petals 5, seldom 

 4, rounded, mostly yellow; stamens usually 20, in two or three 

 rows on the receptacle-tube; style small, terminal or nearly so, 

 not elongating in fruit, neither jointed nor plumose; carpels 

 usually numerous; ovules pendulous, anatropous; receptacles 

 and akenes dry in fruit. 



Cymes leafy; annuals or biennials with small flowers. 



Lower leaves pinnate, upper ternate. P. rivalis. 



Leaves all ternate. 



Petals as long as the sepals. P. monspeliensis. 



Petals much shorter than the sepals. P. biennis. 



Cymes not leafy; perennials; leaves palmate with 5-9 

 leaflets. 

 Leaves densely pubescent on both sides. P. permollis. 



Leaves glabrous at least above. 



Under side of leaflets white tomentose. P. blaschkeana. 



Under side of leaflets green. 



Calyx glandular atomiferous. P. nuttattii. 



Calyx not glandular atomiferous. P. rectiformis. 



Potentilla rivalis Nutt. Annual or biennial; stems erect or ascending, 

 branched above, villous-pubescent, 30-40 cm. high; leaves pinnate, the lower 

 5-foliolate, the cauline usually 3-foliolate; leaflets obovate, cuneate at base, 

 incisely toothed, 2-4 cm. long; cymes loose, leafy, many-flowered; flowers 

 4-6 mm. broad, on slender pedicels, bractlets about as long as the ovate acute 

 calyx-lobes; petals yellow, shorter than the calyx-lobes; akenes smooth, gray. 

 Banks of Snake River. 



