A depressed tufted shrub with thick trifoliolate leaves and small white flowers in terminal cymes. Calyx-tube nearly flat. Bractlets, calyx-lobes and petals 5. Petals obovate, rounded, not clawed. Stamens about 20, borne in 3 series near the base of the receptacle; filaments filiform; anthers cordate. Receptacle hemispheric, bearing numerous pistils. Style filiform, lateral. Achenes swollen, villous. Seed amphitropous, ascending. [Greek, from the similarity of this plant to Sibbaldia procumbens.]

A monotypic genus of eastern North America.

1. Sibbaldiopsis Tridentàta (Soland.) Rydb. Three-Toothed Cinquefoil

Fig. 2258

Potentilla tridentata Soland. in Ait. Hort. Kew. 2: 216. 1789.

Sibbaldiopsis tridentata Rydb. Mem. Dep. Bot. Col. Univ. 2: 187. 1898.

Tufted, woody at the base, much branched, branches erect, 1'-12' high, pubescent with appressed hairs. Stipules lanceolate, entire; leaves mostly petioled, 3-foliolate; leaflets of the lower one oblanceolate, 3-toothed or sometimes 2-5-toothed at the obtuse apex, cuneate at the base, coriaceous, dark green and shining above, pale and minutely pubescent beneath, 1/2'-1' long; upper leaflets linear or oblong, often acute and entire; flowers 1-6, in a terminal cyme, white, 3"-5" broad; bractlets shorter and narrower than the ovate acute calyx-lobes, which are shorter than the obovate-oval petals.

In rocky places, especially on mountains, Greenland to New Jersey, on the higher southern Alleghanies. shores of Lake Superior, and west to Manitoba. Mountain five-finger. June-Aug. Recorded from Scotland, apparently erroneously.