Ross' Avens

Acomastylis turbinata (Rydb.) Greene, Leaflets 1: 174. 1906
Polentilla nivalis Torr. Ann. Lye. N. Y. 1: 32. 1823. Not P. nivalis Lapeyr. 1782
Geum triflorum Torr. Ann. Lye N. Y. 2: 195. 1827. Not G. trijlorum Pursh. 1814.
Geum turbinatum Rydb. Bull. Torrey Club 24: 91. 1897.
Sieversia turbinata Greene, Pittonia 4: 50. 1899.
Sieversia scapoidea A. Nelson; Coult. & Nelson, Man. 263. }?
Acomastylis arapahoensis Daniels, Univ. Mo. Stud. Sci. 2: 146. 1911.
Perennial, with a thick rootstock; stem slender, 0.5-3 dm. high, silky-strigose or glabrate; basal leaves pinnatifid, 5-15 cm. long, silky-strigose or glabrate; segments 11-33, oblanceolate, obovate, or cuneate in outline, 3-5-cleft or toothed, with lanceolate or oblong teeth or lobes; stem-leaves 1-3, pinnatifid with 3-13 lanceolate divisions; hypanthium obconie-turbinate, about 5 mm. high and broad; bractlets and sepals often tinged with purple, the former 3-4 mm. long, lanceolate, the latter ovate, short-acuminate, 5-6 mm. long; petals yellow, broadly obovate or obcordate, 6-8 mm. long; body of the achenes 2.5-3 mm. long, strigose; style 3-4 mm. long.
Type locality: Rocky Mountains [Colorado].
Distribution: Mountains, from Montana to New Mexico, Arizona, and Nevada.

Acomastylis gracilipes (Piper) Greene, Leaflets 1: 174. 1906
Potentilla gracilipes Piper, Bull. Torrey Club 27: 392. 1900. Sieversia gracilipes Greene, Leaflets 1: 4. 1903.
Perennial, with a thick rootstock and caudex; basal leaves many, pinnatifid, silverysericeous on both sides, 4-6 cm. long; divisions 9-15, broadly cuneate in outline, three-cleft at the apex or entire; stem 1 -flowered, 6-8 cm. long, pubescent; stem-leaves 1 or 2, entire or 3-lobed, small; hypanthium saucershaped or nearly so, silky-strigose; bractlets elliptic, smaller than the sepals; sepals broadly ovate, acutish, 6-7 mm. long; petals orbicular, 1 cm. long.
Type locality: Face of north cliffs, Blue Mountains, head of Anthony's Creek, Oregon. Distribution: Known only from the type locality.

Acomastylis depressa Greene, Leaflets 1: 174. 1906
Perennial, with a very thick rootstock and caudex; stem less than 1 cm. high, scapiform, one-flowered; basal leaves numerous, 3-5 cm. long, pinnatifid; divisions 15-21, crowded, about 1 cm. long, cuneate in outline, usually 3-cleft, silky as well as glandular-pruinose; stem-leaves few, greatly reduced, simple or 3-5-divided; hypanthium saucer-shaped or nearly so; bractlets lanceolate, 3-4 mm. long; sepals ovate, 6-7 mm. long; petals orbicular or somewhat obcordate, 7-8 mm. long.
Type locality: Mount Stewart, Washington. Distribution: Known only from the type collection.