1. Oonopsis multicaulis (Nuttall) Greene, Pittonia. 3: 45. 1896.
Yellow-rayed or branched goldenweed
Stenotus multicaulis Nuttall, Trans. Amer. Philos. Soc., n. s. 7: 335. 1840; Haplopappus multicaulis (Nuttall) A. Gray; Oönopsis argillacea A. Nelson
Plants 2–11(–14) cm. Stems sparsely villosulous, glabrescent at maturity. Leaf blades linear to linear-oblanceolate, 7–85 × 0.8–4.2(–5) mm, cauline bases not auriculate or clasping, distalmost abruptly reduced in size. Heads not immediately subtended by leafy bracts. Involucres 6–10 mm. Phyllary apices abruptly acute to obtuse, apiculate to cuspidate. Ray florets 5–11. Disc florets 12–25. Cypselae 2.8–4 mm, faces tomentose. 2n = 8.
Flowering Jun–Jul(–Aug). Barren selenium and/or alkaline hills and flats, loose shaley, clay-shale, and sandy-clay soil, pastures, eroded clay pans in mid-grass prairie with Artemisia, sometimes with Atriplex; 1100–1900 m; Mont., Nebr., S.Dak., Wyo.
Oönopsis multicaulis grows in Carter County in Montana, Dawes and Sioux counties in Nebraska, Butte and Fall River counties in South Dakota, and Campbell, Carbon, Converse, Crook, Fremont, Johnson, Natrona, Niobrara, Platte, and Weston counties in Wyoming.