3. Potentilla norvegica L. (rough cinquefoil, Norwegian cinquefoil)

P. norvegica var. hirsuta (Michx.) Lehm.

P. norvegica var. labradorica (Lehm.) Fernald

Pl. 535 h–j; Map 2466

Plants annual or biennial, rarely short-lived perennial herbs. Stems 5–60 cm long, erect or ascending, moderately to densely pubescent with straight to somewhat woolly hairs, the hairs often with minute, pustular bases, rarely glabrous or nearly so. Leaves with the petioles 1–6 cm long, sometimes nearly sessile toward the stem tips, these hairy. Stipules 5–20 mm long, ovate, sharply pointed at the tip, the margins entire or toothed and often hairy, the surfaces hairy. Leaf blades 2–6(–8) cm long, palmately or pinnately trifoliate, a few of the leaves rarely with 5 leaflets, these 1–6(–8) cm long (the central leaflet the largest, sessile or short-stalked), broadly oblanceolate or elliptic to obovate or broadly obovate, rounded to bluntly pointed at the tips, the margins coarsely toothed, the upper surface green, glabrous or sparsely to moderately hairy, especially along the veins, the undersurface lighter green, moderately hairy, especially along the veins. Inflorescences terminal, relatively small, flat-topped to shallowly dome-shaped clusters of several flowers. Bractlets 4–8 mm long, oblanceolate to narrowly elliptic, moderately hairy. Hypanthia 4–5 mm in diameter, shallowly cup-shaped to nearly disc-shaped. Sepals 3.5–6.0 mm long, broadly ovate, sharply pointed at the tips. Petals 3–5 mm long, obovate, shallowly and broadly notched at the tip, yellow. Stamens (15–)20. Ovaries with the styles attached near the tips. Fruits 0.8–1.2 mm long, the surface usually coarsely wrinkled or longitudinally ribbed, brown to greenish brown, unwinged. 2n=42, 56, 63, 70. May–October.

Scattered, mostly in the western and northern halves of the state (U.S. [including Alaska]; Canada, Mexico, Greenland, Europe, Asia). Banks of streams and rivers, margins of ponds, lakes, and oxbows, bases of bluffs, bottomland prairies, moist swales of upland prairies, sand prairies, and bottomland forests; also pastures, fallow fields, crop fields, barnyards, railroad, roadsides, and open, disturbed areas.