Potentilla breweri

Potentilla breweri is a species of Potentilla known by the common name Brewer's cinquefoil.

It is native to western North America, with populations scattered from southern Washington to south-central California and from the Pacific cordillera inland to the mountains of the Great Basin. Its greatest population density occurs in the Sierra Nevada, the high Cascade Ranges, and Steens Mountain.

Description
P. breweri is a herbaceous perennial or near-subshrub growing from a sturdy, branched woody caudex. Its leaves are pinnately compound and covered in soft, tangled, woolly hairs, giving them a more or less silver-blue color. The exact shape of the leaf and the degree of hairiness can vary substantially between early-season leaves and those produced later in the year. The inflorescences are cymose and usually bear 2-15 flowers. Like most Potentilla species, its flowers have five bright yellow petals, 15 stamens, and numerous separate pistils, and are adapted for generalist pollination. Each flower produces a cluster of achenes if successfully pollinated.

It is a taxonomically difficult species that appears to hybridize frequently with other Potentilla spp. The boundaries of the resulting species complex are poorly-understood.

Habitat and ecology
The plants are found in high-montane to subalpine meadow openings. They prefer seasonally-wet habitats with little competition for sunlight, such as rocky meadows and rock crevices, and are often found near lakes and streams. They range in altitude from 1500 to 3600 m.

History
The P. breweri complex (P. breweri, P. drummondii, and P. bruceae) was one of the case studies used in Clausen, Keck, and Hiesey's biosystematic work.