Syn. Pl. 2: 458. 1807.
Annuals, perennials, or subshrubs [shrubs], (20–) 30–70 [–250+] cm. Stems erect, branched from bases or throughout. Leaves cauline; mostly opposite (distal sometimes alternate); petiolate or sessile; blades (or lobes) ovate, oblanceolate, or linear, 1-pinnately lobed, ultimate margins ± toothed (teeth often bristle-tipped), faces glabrous or ± hirtellous to scabrellous (oil-glands usually borne at bases of lobes and subterminally near apices). Heads usually radiate, rarely discoid, borne singly. Calyculi of 3–5 or 12–22 linear to subulate bractlets (sometimes with 1–2 lobes, often bristle-tipped, usually bearing oil-glands). Involucres campanulate to obconic [hemispheric], [5–] 7–20+ mm diam. Phyllaries persistent, 8–20+ in ± 2 series (weakly connate 1/3–3/4 their lengths, separating in age, mostly lanceolate to linear, margins of outer distinct to bases or nearly so, oil-glands in faces and near margins). Receptacles convex, ± pitted (socket margins fimbrillate to setose), epaleate. Ray-florets usually 7–16 [–16], rarely 0, pistillate, fertile; corollas yellow to orange or red-orange. Disc-florets 25–70 [100+], bisexual, fertile; corollas yellow to yellow-orange, tubes shorter than cylindric throats, lobes 5, lanceovate to lance-linear. Cypselae obpyramidal [obconic], glabrous or ± strigose or sericeous; pappi persistent, of 8–20 scales in 1–2 series (single scales muticous, or unequally 3-aristate, or comprising 5–11 basally connate bristles). x = 7, 13.
sw United States, Mexico, Central America
Species 10 (3 in the flora).
|1||Annuals; calyculus bractlets eglandular; pappi: outer scales erose, inner each unequally 3-aristate||Adenophyllum wrightii|
|1||Perennials or subshrubs; calyculus bractlets bearing oil-glands; pappi: each scale comprising 5–11 basally connate bristles||> 2|
|2||Leaves 3–5-lobed (lobes linear to cuneate or oblanceolate, ultimate margins entire or toothed); disc florets 25–40; pappi of 8–12 scales||Adenophyllum porophylloides|
|2||Leaves not lobed (blades ovate to oblanceolate, margins toothed); disc florets 50–80; pappi of 15–20 scales||Adenophyllum cooperi|