Potentilla bipinnatifida (Plains Cinquefoil) - photos and description

Potentilla bipinnatifida

Potentilla bipinnatifida

Potentilla bipinnatifida

Potentilla bipinnatifida

Potentilla bipinnatifida
Basal leaf in above photo

Potentilla bipinnatifida
Leaf top (top of above photo) and leaf underside (bottom of above photo)

Potentilla bipinnatifida
Stem leaf in above photo

General: Perennial with a branching caudex, stems one to several, stems branching above.

Flowers: Flowers in congested cymes at stem ends. Flowers are bright yellow, measured to 10 mm diameter. The sepals about as long as the petals, the outer row of bracts, shorter and narrower than the sepals. Flowers have up to 20 stamens.

Leaves: Basal leaves pinnate with up to 11 leaflets (most basal leaves had 9 leaflets), the leaflets pectinately divided almost to midrib (pectinately = pinnatifid with narrow, closely set segments; comb-like). Basal leaf measured to 16.5 cm long and 6 cm wide (including petiole). Stem leaves reduced in size upwards and sessile towards the top of stems. Top side of leaves grey-green in colour, leaf bottoms are white woolly.

Height: Height is listed in Budd's Flora to 50 cm, we measured plants to 25 cm tall.

Habitat: Dry prairie and open slopes.

Abundance: Common.

Origin: Native.

Similar species: This plant is very similar to P. pensylvanica. Reading through various prairie floras, the difference between the two species is trivial; the only reliable difference I could find between the two is the ratio of the length of the bractlets of the epicalyx to the sepals. From Flora of Alberta: "P. bipinnatifida has "bractlets of epicalyx oblong-lanceolate, shorter and narrower than sepals", while P. pensylvanica has "bractlets about as long as sepals or slightly longer".

Budd's Flora
distinguishes based on the colour of the undersides of the leaflets, which is so open to interpretation I find it useless - P. bipinnatifida has "leaflets white tomentose below", while P. pensylvanica has leaflets "grayish pilose to hirsute below".

When and where photographed: The above photos were taken June 24th on prairie on a south facing slope, South Saskatchewan River valley, about 250 km west of our home in Regina, SK.