Prairie Cinquefoil is a native perennial erect forb from 1 to 2+ feet high on stems covered with fine white spreading hairs.
The leaves are pinnately divided with the most basal leaves on long stalks; the leaf has 7 to 11 stalkless ovate leaflets, placed in separated pairings with one terminal leaflet. Upper stem leaves have fewer leaflets. Leaflets have a coarsely serrated margin with some serrations looking like small notched lobes. Leaflets enlarge in size toward the tip and leaflets and leaf stalk have the same covering of hair as the stem. The terminal leaflet tip is obtuse to acute, not rounded. The surfaces are medium green with a pinnate venation although the underside will appear paler due to many whitish hairs with longer hair on the main veins. Upper stem leaves will be smaller with fewer leaflets.
The inflorescence a narrowly branched tightly stalked cluster (a cyme) atop the stem. Cluster stalks are glandular hairy.
The flowers are perfect, 5-parted with 5 light green sepals of the calyx with very pointed tips and alternating between them 5 smaller floral bractlets, slightly darker green, which are not quite as long as the sepals but are hidden behind the petals when the flower is open. Both bractlets and sepals are very hairy. The 5 petals of the corolla are white to nearly white. These are broader than the sepals but also have pointed tips and are just as long and alternate in placement with the green sepals. The inner throat of the corolla forms a pentagonal glandular structure (a theca - which produces the pollen) from which arise the 20 to 30 stamens which have yellow anthers. The pollen turns a reddish brown at maturity. In the center is the rounded yellow female reproductive structure composed of 10 to 80 carpels. Both the petals and the sepals have a noticeable venation which helps insects find the nectary. The entire flower is only 1/2 inch wide.
Seed: Fertile flowers produce many light brown 1/32 inch long dry tear-drop shaped achenes which are enclosed in the partially open calyx until shaken out by the wind. Seeds are small and light - 230,000 to the ounce, and require 60 days of cold stratification for germination plus light and cool soil - best to plant in the fall and let winter to the work.
Varieties: No longer recognized in the re-classification.
Habitat: Prairie Cinquefoil prefers mesic to dry soil conditions, full to partial sun in various soils. The root system is rhizomatous with a stout taproot. It is tolerant of dry conditions.
Names: With the publication of new volume 9 of Flora of North America this species has been removed from the Potentilla genus and classified as Drymocallis arguta (Pursh) Rydb. The genus name, Drymocallis, is from two Greek words - dymos, meaning 'woods' and kallos meaning 'beauty', referring to the plant as a 'woodland beauty'. The species name, arguta, means 'sharply tooted' or 'notched' referring to the teeth on the margins of the leaflets. The older classification was Potentilla arguta and there were two varieties, which are not recognized in the new classification. See Flora of North America (Ref. #W7) for a description and rational for the class change.
The author names for the plant classification are: First to classify was ‘Pursh’ which refers to Frederick Traugott Pursh (1774-1820) German-American botanist who wrote A Systematic Arrangement and Description of the Plants of North America, and was the botanist who catalogued and described the plants brought back by the exploring expedition of Lewis and Clark. His work was amended by ‘Rybg.’ which refers to Per Axel Rydberg (1860-1931), Swedish born American botanist, first curator of the New York Botanical Garden Herbarium. He received a commission from the US Dept. of Agriculture for a botanical exploration of several places in the western states and his expertise was in the flora of the Great Plains and Rocky Mountains. He described approx. 1700 new species.
Comparisons: There is one other similar white-flowered species in the Cinquefoil group found in Minnesota: Sibbaldiopsis tridentata, [formerly Potentilla tridentata], Shrubby five-fingers or the Three-toothed Cinquefoil but there the leaves are divided into 3 leaflets and the sepals are much shorter than the petals. All the other similar looking Cinquefoils have yellow flowers.
Above left: 1st photo - The 5 petals of the corolla are broader than the sepals but just as long and alternate in placement with the green sepals. The inner throat of the corolla forms a pentagonal glandular structure from which arise the 20+ stamens which surround the rounded yellow female reproductive structure composed of many carpels. 2nd photo - Alternating between the 5 sepals are 5 smaller floral bractlets, slightly darker green, which are not quite as long as the sepals but are hidden behind the petals when the flower is open. Both bractlets, sepals and stalks are glandular hairy.
Below: The stem leaves have fewer leaflets and the leaflets are more narrow. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: 1st photo - The more basal leaves have long stalks and 7 to 11 leaflets. 2nd photo - Only the terminal leaflet has a stalk. Stalks are hairy. 3rd photo - The root is rhizomatous and develops a stout taproot.
Below: 1st photo - The leaf underside is very hairy with longer hair on the main veins. 2nd & 3rd photos - The inflorescence is atop a tall stem well above the uppermost leaf as seen in the 3rd photo. Note the darker color of the pollen at maturity.
Below: 1st photo - The drying seed capsule retain the dense hair of the calyx. 2nd photo - Each capsule contains many brown 1/32 inch long dry achenes which are enclosed in the partially open calyx until shaken out by the wind.
Notes: Prairie Cinquefoil should be considered indigenous to the Garden area. While Eloise Butler had not reported it in the first years after the Garden was established she discovered it growing at the south end of the Garden on July 27, 1915. She brought in two plants in Oct. 1919 from Columbia Heights. More were added in 1925 and '27. Martha Crone planted it in 1946 when she was developing the new Upland Garden.
Prairie Cinquefoil is native to most of Minnesota with only a few widely scattered county exceptions. In North America it is known throughout the U.S. from the Rockies eastward but north of the states along the Gulf Coast and north of the Atlantic coast states up through North Carolina. In Canada it is found from Alberta eastward except the Maritime Provinces. It is the only species of Drymocallis found east of the Rocky Mountains except for D. fissa found in the vicinity of the Black Hills.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"