Asclepias hirtella

Asclepias hirtella is a tall perennial, reaching 3 feet in height. It has many narrow, linear leaves that are produced alternately on the stem. Its flowers in lateral umbels with slender peduncles. Each stem may have 2 to 10 umbels and each umbel may have 30 to 100 flowers. The flowers lack horns and are greenish to slightly purplish in color. It flowers June through August.[1][3][4]

This species closely resembles Asclepias longifolia, and it is occasionally treated to be a subspecies of it. Asclepias longifolia is restricted to the Southeastern Coastal Plain, and it differs from Asclepias hirtella in its fewer and smaller flower umbels, and its glabrous leaves.[5]

Asclepias hirtella is found in a variety of open habitats, including areas with dry sandy soil, prairies and limestone glades,[6][5] It can be found in both wet and dry conditions, and it prefers open habitats with full sun.[1] This species is a component of high-quality grassland communities, although it can be found in and disturbed conditions as well.[1][7] It is considered to be uncommon throughout much of its range.[1][6]

Asclepias hirtella is native to West Virginia, Ohio, Michigan and Wisconsin to northern Iowa, Kansas and Oklahoma to southwestern Kentucky.[8] It is a prairie species native to 13 US states and one Canadian province, but is becoming rare or declining in numbers in parts of its native range.[4] A. hirtella is rare in Minnesota and listed as a threatened species in that state, where it occurs in the south eastern corner in mesic prairie habitats.[4]