Brook Cinquefoil

Potentilla michoacana Rydb. Mem. Dep. Bot. Columbia
Univ. 2 : 44. 1898.
Spreading from an annual root, finely pubescent, divergently branched ; leaves ternate with shortly stalked terminal leaflets ; leaflets narrowly cuneate, few-toothed above the middle, 1-2 cm. long, finely puberulent; bractlets oblong, about equaling the broadly ovate sepals; petals white, obovate, truncate, half the length of the sepals; stamens 5.
Type locality : State of Michoacan, Mexico. Distribution : Known only from the type locality.

Potentilla rivalis Mutt.; T. & G. Fl. N. Am. 1: 437. 1840
Tridop hy Hum rivale Greene, Leaflets 1 : 189. 1905.
Stem erect and simple, branched above, often tinged with brown or purple, finely villous-hirsute, leafy; stipules broadly ovate, 1-2 cm. long, often coarsely toothed; lower leaves pinnate with two pairs of approximate leaflets, the upper trifoliolate, sometimes all trifoliolate ; leaflets 2-5 cm. long, obovate, with coarse ovate teeth ; cyme leafy, with ascending branches; flowers on short pedicels, less than 5 mm. in diameter; hypanthium hirsute, in age about 5 mm. in diameter; bractlets oblong, obtuse or acute, about 3 mm. long, rather shorter than the ovate acute sepals ; petals cuneate, much shorter than the sepals ; -stamens about 10; pistils numerous; styles terminal, fusiform; achenes smooth.
Type locality : Alluvial soil alongLewis River [Snake River].
Distribution : River valleys from British Columbia to Saskatchewan and Mexico.

Potentilla pentandra Engelm.; T. & G. Fl. N. Am
1: 447. 1840.
Potentilla rivalis pentandra S. Wats. Proc. Am. Acad. 8 : 553. 1873. Potentillopsis Engelmanniana Opiz, Lotos 7 : 30. 1857. Tridophyllum pentandrum Greene, Leaflets 1 : 189. 1905.
Annual; stems stout, very leafy, 3-7 dm. high, erect, often tinged with brown, finely hirsute and much branched above; stipules broadly ovate-acuminate, 1-2 cm. long, deeply toothed; lower leaves pedately 5-foliolate, or 3-foliolate with the lateral leaflets 2-cleft, with hirsute petioles 3-8 cm. long ; the uppermost 3-foliolate and very short-petioled ; leaflets 2-10 cm. long, oblong to oblanceolate or cuneate, deeply serrate, pubescent, on both sides ; cyme very dense and leafy, in age, as a rule, flat-topped ; flowers on short hirsute pedicels, less than 5 mm. in diameter; hypanthium sparingly hirsute and finely pubescent, in age about 5 mm. in diameter ; bractlets oblong, acute, about 3 mm. long, nearly as long as the ovate acute sepals but much narrower ; petals pale-yellow, obovate, scarcely half a& long as the sepals ; stamens seldom more than 5, very small, with didymous anthers ; pistils exceedingly numerous ; styles terminal, short-fusiform and glandular below ; achenes smooth, brownish.
Type locality: Fort Gibson, Arkansas.
Distribution : Bottom-land, especially in sandy soil, from Missouri and Arkansas to Saskatchewan, Alberta, and Nebraska.

Potentilla rivalis is a species of cinquefoil known by the common names brook cinquefoil and river cinquefoil. It is native to much of North America, including the southern half of Canada and the western and central United States. It grows in moist habitat, sometimes in disturbed areas. It is an annual or biennial herb producing upright stems up to half a meter tall from a taproot. The hairy leaves are divided into three to five leaflets which are lance-shaped to oval and lined with teeth. The inflorescence is a cluster of several flowers with tiny yellow petals no more than 2 millimeters long on a calyx of pointed sepals and bractlets which are slightly longer.