Chaenactis sect. Acarphaea
Annuals; proximal indument predominantly ± farinose, not arachnoid. Stems usually 1, erect; branches mainly distal. Leaves: largest blades deltate to ± ovate [broadly elliptic], (2–)3–4-pinnately lobed, not gland-dotted. Heads discoid (mostly 3–20+ per stem). Peduncles ascending to erect. Phyllaries: outer acute to acuminate-aristate. Florets: corollas white to pinkish, actinomorphic, ± equal. Cypselae ± terete or compressed; pappi 0, coroniform (of ± 10 scales), or of 4(–5) [10–16] scales in 1 [2–3] series. x = 8.
sw United States, nw Mexico.
Species 3 (2 in the flora).
|1||Phyllaries: apices (all or inner) usually reddish, acuminate, aristate, terete; receptacles: paleae (0–)3–10+ (± phyllary-like, apices visible among mature floret buds); leaves: ultimate lobes ± terete; cypselae ± terete; involucres mostly 5–10 mm diam||Chaenactis carphoclinia|
|1||Phyllaries: apices (all) ± green, acute or scarcely acuminate, not aristate, ± plane; receptacles: paleae 0; leaves: ultimate lobes plane or involute; cypselae compressed; involucres mostly 10–25 mm diam||> 2|
|2||Pappi 0 or coroniform (of ± 10 scales, longest 0.1–0.5 mm); involucres mostly 10–15 mm diam.; phyllaries ± densely villous, not or sparsely glandular||Chaenactis artemisiifolia|
|2||Pappi of 10–16 scales in 2–3 subequal series, longest scales 4–6 mm; involucres mostly 20–25 mm diam.; phyllaries ± glandular, not or sparsely villous||Chaenactis lacera (see 1 Chaenactis artemisiifolia)|