Potentilla pensylvanica (Pennsylvania Cinquefoil)
|Also known as:||Prairie Cinquefoil|
|Habitat:||sun; dry sandy, gravelly or rocky soil; rock outcrops, prairies, roadsides, along railroads, grassy slopes|
|Bloom season:||June - August|
|Plant height:||8 to 16 inches|
|Wetland Indicator Status:||GP: FACU MW: FACU NCNE: FACU|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Branching cluster at the top of the stem, the flowers mostly short-stalked and congested at branch tips. Flowers are yellow, about ½ inch across, with 5 broad petals that are tapered at the base and rounded to notched at the tip. In the center are about 20 yellow stamens.
The calyx cupping the flower has 5 triangular sepals, pointed at the tip, that are about as long as the petals. Behind each petal, alternating with the sepals, is a lance-elliptic bractlet, blunt to pointed at the tip, about as long as or slightly longer than the sepals. The calyx and flower stalks are covered in short hairs.
Leaves and stems:
Leaves are mostly basal and alternate on the lower stem, pinnately compound with 5 to 13 leaflets arranged on the upper half or more of the stalk, the stalk below the lowest leaflet 3/8 to 3+ inches (1 to 8 cm) long. Leaflets are oblong-elliptic in outline, the largest to ~2 inches (1.5 to 5 cm) long, the edges with fewer than 10 large teeth or narrow lobes per side, cut usually more than halfway to the midvein and the edges rolled under. The lowest leaflets are smallest, becoming larger as they ascend the stalk. The uppermost stem leaves are much smaller and stalkless or nearly so.
The upper surface is green to gray-green and variably covered in a mix of long and short hairs, the lower surface gray-green to whitish and densely hairy. Stems are multiple from the base, erect to ascending to prostrate from the base before rising up (decumbent), unbranched except in the flower clusters and moderately to densely covered in a mix of long and short hairs.
The sepals fold up, creating a capsule-like container, and eventually turn dark brown. Inside are many brown seeds, 1.2 mm long with a wrinkly texture. The old fruiting stems can persist through winter.
Pennsylvania Cinquefoil is found primarily in the western third of the state with a few scattered locations in the Arrowhead region; habitats include gravel and sand prairies, rock outcrops, gravel pits and grassy slopes. At one time there were several recognized varieties of P. pensylvanica in Minnesota, most of which are now considered either separate species or lumped into P. pensylvanica: var. bipinnatifida (now Potentilla bipinnatifida), var. arida (P. lasiodonta), var. litoralis (P. litoralis), and var. pensylvanica (described above). There are close to 100 species of Potentilla in North America and these are all part of a group known as Potentilla section Pensylvanicae.
The stand-out characteristics of the complex are: overall hairy with long and/or short hairs; leaves mostly basal with 1 to 4 stem leaves; leaflets with large teeth or narrow lobes, the lobes cut about halfway or more to the midvein and the edges rolled under (revolute); branching flower clusters, the 5-petaled, yellow flowers mostly congested at branch tips. What can differentiate the species are the length of sepals and bractlets relative each other and to the flower petals; type of hairs (long, short, silky, woolly, etc.); number of teeth/lobes on leaflets; how leaflets are arranged on the stalk; whether glands are present and the abundance.
P. pensylvanica leaflets of basal leaves are arranged along half or more of the stalk, have fewer than 10 lobes per side, the lobes cut ¾ or more to the midvein, and have a mix of long and short silky hairs; sepals, bractlets and petals are all near equal in length; leaves and calyces are usually abundantly glandular, though we do not currently have photographic evidence of this.
By comparison, P. bipinnatifida and P. litoralis leaflets are mostly concentrated on the upper 1/3 of the stalk, lack short hairs, glands are absent or sparse, and bractlets are only about 2/3 as long as sepals, those of P. litoralis more linear than those of P. bipinnatifida. P. lasiodonta leaflets have up to 21 teeth/lobes per side, are only cut about halfway to the midvein, and bractlets are 1 to 2 times as long as the sepals.
Side note: we have encountered what we assumed was P. bipinnatifida (or possibly P. litoralis) a number of times, based only on the arrangement of leaflets on basal leaves, but reviewing images of flowers does not show the expected shorter bractlets. We'll have to revisit some of these sites before we can make a final determination.
Miscellaneous factoid: Pennsylvania Cinquefoil is not native to Pennsylvania!
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- Pennsylvania Cinquefoil plant
- Pennsylvania Cinquefoil in a prairie
- Pennsylvania Cinquefoil in gravelly soil
- Pennsylvania Cinquefoil in a rock outcrop with Prickly Pear cactus
- basal rosettes in early June
- flowers are in small clusters at branch tips
- comparison of Potentilla lasiodonta and P. pensylvanica calyces
- comparison of Potentilla lasiodonta and P. pensylvanica leaflets
Photos by K. Chayka taken in Cook, Polk and Pope counties. Photos by Peter M. Dziuk taken in Pope, Rock and Stearns counties.
Have you seen this plant in Minnesota, or have any other comments about it?