Psilostrophe sparsiflora

Psilostrophe sparsiflora, commonly known as greenstem paperflower, is a species of flowering plant in the family Asteraceae. It is native to Arizona, New Mexico, and Utah in the southwestern United States.

Description

Psilostrophe sparsiflora is a biennial or perennial forb or subshrub, typically tall. Its single or clustered stems are greenish and often hairy. The basal leaves are narrow to spatula-shaped and may have entire or irregularly lobed margins; leaves higher on the stem are smaller, alternate, and stalkless.

The yellow flower heads occur in loose clusters, usually in groups of three to six. Each head has both ray and disc florets, and the ray florets bend downward as the fruit develops. In Arizona, flowering has been recorded from May through November.

Taxonomy

Asa Gray first described the plant in 1884 as Riddellia tagetina var. sparsiflora. Aven Nelson raised it to species rank under its current name in 1903. Plants of the World Online recognizes Psilostrophe sparsiflora as an accepted species.

Distribution and habitat

The species occurs naturally in Arizona, New Mexico, and Utah. It grows on dry mesas and slopes, including grasslands, pinyon–juniper woodland, open pine forest, and other upland woodland. The University of Arizona records it from elevations of about . In Utah it is found on the eastern side of the High Plateaus in Kane, Garfield, and Wayne counties, where it may be locally abundant and generally flowers from May to October.