Prairie Burnet

Poteridium annuum (Nutt.) Spach, Ann. Sci. Nat. III. 5 : 43. 1846
Poterium annuum. Nutt.; Hook. Fl. Bor, Am. 1 : 198. 1832. Sanguisorba annua Nutt.; T. & G. Fl. N. Am. 1 : 429. 1840.
Glabrous annual or perhaps rather biennial, with a tap-root ; stem branched, leafy, 1^1dm. high ; leaves odd-pinnate; stipules of the basal leaves entire, those of the stem-leaves pectinately divided ; leaflets 7-15, broadly obovate, 7-12 mm. long, pectinate-pinnatifid with obtuse, linear-oblong or linear, mostly spreading divisions ; spikes at the ends of the branches, oblong-cylindric to globose, 0.5-3 cm. long, about 7 mm. thick ; bracts and bractlets ovate, shorter than the flowers, scarious-hy aline ; sepals broadly oval, apiculate, 2 mm. long, green with broad white-scarious margins ; stamens usually 4 ; filaments filiform, short ; fruiting hypanthium ovoid, 2.5 mm. long, with strong thin wings, which are nearly 0.5 mm. wide, faces not reticulate.
Type locality : Plains of Red River, Arkansas. Distribution : From Arkansas to Kansas and Texas.

Sanguisorba annua is a species of flowering plant in the rose family known by the common names annual burnet and prairie burnet. It is native to North America, including many areas in western and central Canada and the United States. It can be found in several types of habitat, including grassland, sagebrush, and disturbed areas. It is an annual or biennial herb producing a leafy, mostly erect stem up to about 90 centimeters in maximum height. The leaves are composed of several pairs of leaflets, each leaflet oval in shape and usually divided into lobes, sometimes deeply, the lobes becoming narrow, linear, or fingerlike. The inflorescence is a spikelike dense cluster of up to 50 flowers held erect on a tall, naked peduncle. The flower has four green sepals and no petals.