Pittonia3: 45. 1896
w, c United States.
Species 4 (4 in the flora).
Oönopsis is characterized by a relatively low habit, woody taproots with ample vegetative reproduction via one or two horizontal, spreading, sprouting branch roots, root crowns bearing woody, branched caudices, even-sized cauline leaves continuing up the stems and subtending the heads, foliaceous outer phyllaries, and yellow rays (in two species). All taxa are selenium-accumulating and indicators of selenium substrates. An undescribed fifth species has been noted (G. K. Brown 1993) from Pueblo and Fremont counties, Colorado; it is closely related to Oönopsis foliosa.
|1||Leaf blades linear to linear-oblanceolate, 0.7–5 mm wide; involucres 6-–11.5(–13) mm; phyllary apices abruptly acute to obtuse, apiculate to cuspidate; disc florets 7–28||> 2|
|1||Leaf blades oblanceolate to narrowly obovate or oblong-oblanceolate, 2–16 mm wide; involucres 10–25 mm; phyllary apices long-acuminate to long-acute, not apiculate or cuspidate; disc florets 10–45 or 53–150||> 3|
|2||Ray florets 5–11; cypselae 2.8–4 mm, tomentose||Oönopsis multicaulis|
|2||Ray florets 0; cypselae 5–6 mm, glabrous or sparsely scabrous||Oönopsis engelmannii|
|3||Stems glabrous; cauline leaves not auriculate or clasping; heads not immediately subtended by leaflike bracts, distalmost cauline abruptly reduced in size; ray florets 0; disc florets 10–45||Oönopsis wardii|
|3||Stems villosulous or glabrous; at least distal cauline leaves subauriculate and subclasping; heads immediately subtended by leaflike bracts similar to distal cauline leaves; ray florets 15–25 or 0; disc florets 53–150||Oönopsis foliosa|
|Author||Gregory K. Brown + and Guy L. Nesom +|
|Basionym||Stenotus Oönopsis +|
|Etymology||Greek oön, egg, and - opsis, likeness, alluding to a perceived egglike appearance of heads +|
|Illustrator||Linny Heagy +|
|Reference||bricker1998a +, brown1989a +, brown1993a + and evans1991a +|
|Synonym||Haplopappus Oönoopsis +|
|Taxon name||Oönopsis +|
|Taxon parent||Asteraceae tribe Astereae +|
|Taxon rank||genus +|
|Volume||Volume 20 +|