Rose family (Rosaceae)
Description: This perennial wildflower is about 2-5' tall. The stems are light green and glabrous (or nearly so). Alternate compound leaves up to 1½' long are located mostly along the lower half of each plant; they are widely spreading. Each compound leaf is odd-pinnate with 7-15 leaflets. The leaflets are about 1-2½" long and a little less than one-half as much across; they are oblong in shape and coarsely serrated along their margins. Some leaflets are a little wider toward their bases than their tips. Upper leaflet surfaces are medium green and glabrous, while their lower surfaces are a slightly lighter shade of green. The leaflets have short petiolules (short slender stalklets) at their bases that connect them to the rachis (central stalk) of the compound leaf. The compound leaves have petioles up to 6" long. Coarsely toothed stipules are located at the bases of the petioles.
Upper stems terminate in cylindrical spikes of whitish flowers about 2-8" long and 1" across. The long naked peduncles of the floral spikes are light to medium green and glabrous; they are either unbranched or divide into 2-3 erect stalks, with each stalk bearing a floral spike at its apex. There is a small toothed bract at the base of each division. The flowers are densely packed together all around the central axis of the spike. Each flower consists of a calyx with 4 spreading lobes, 4 long exerted stamens, and a pistil; there are no true petals. The petaloid calyx is greenish white to white and about ¼" across. The stamens (about ½" long) have long white filaments that are very conspicuous. Because of these abundant filaments, the floral spike resembles a white bottlebrush. The blooming period occurs from mid-summer to early fall and lasts about 1-2 months. During the fall, the flowers are replaced by 4-winged capsules that each contain a single seed. These small capsules (about ¼" long) can probably float on water. The root system at the base of the plant is stout and rather woody from its abundant tannins; it usually develops underground runners that form vegetative offsets.
Cultivation: The preference is full sun, wet to moist conditions, and soil containing some organic matter.
Range & Habitat: The native American Burnet has been found in only a few counties of Illinois. It is quite rare and state-listed as 'endangered.' Illinois lies at the western range limit for this species. This wildflower is more abundant in some areas of New England and the Mid-Atlantic states. In Illinois, American Burnet has been found in wet to moist prairies (primarily along railroads) and fens. In other states, it has been found in low areas along rivers, peaty bogs, and swamps.
Faunal Associations: Remarkably little appears to be known about floral-faunal relationships for this plant. The odd-looking flowers produce abundant pollen and possibly some nectar; they attract various bees (including honeybees) and probably other insects. The leaves are somewhat bitter from the presence of tannins and saponins, but it is unclear to what extent this deters mammalian herbivores from consuming them.
Photographic Location: A prairie in Fayette County, Illinois. The flowering plant was photographed by Keith & Patty Horn (Copyright © 2009).
Comments: American Burnet is an attractive wildflower that should be cultivated in gardens more often. This is the only native Sanguisorba sp. (Burnet) in Illinois and the surrounding area. Two European species that are occasionally cultivated, Sanguisorba officinalis (European Great Burnet) and Sanguisorba minor (Garden Burnet), are smaller in size and they have less attractive purple or brown flowers on shorter spikes. While these latter two species occasionally escape into the wild, they do not appear to be aggressive in our area. Another common name of Sanguisorba canadensis is Canadian Burnet.