Biennials, perennials, or subshrubs (rarely flowering first-year); proximal indument predominantly arachnoid, lanuginose, or pannose (rarely glabrescent), not farinose. Stems 1–25+, prostrate to erect; branches mainly proximal. Leaves: largest blades deltate, elliptic, linear, or ovate, (0–) 1–2-pinnately or -subpalmately lobed, glanddotted beneath indument. Heads discoid. Peduncles prostrate to erect. Phyllaries: outer ± blunt. Corollas white to pinkish or cream, actinomorphic, ± equal. Cypselae ± terete; pappi of (8–) 10–20 scales in 2–4 equal or gradually unequal series. x = 6.

Distribution

w North America, nw Mexico

Discussion

Species 8 (8 in the flora).

Species of sect. Macrocarphus occur mainly in montane to alpine habitats; all except Chaenactis douglasii are narrowly distributed. With C. douglasii here broadly defined, all the species of sect. Macrocarphus are sharply distinct.

Selected References

None.

Lower Taxa

Chaenactis alpigena, Chaenactis douglasii, Chaenactis evermannii, Chaenactis nevadensis, Chaenactis parishii, Chaenactis santolinoides, Chaenactis suffrutescens, Chaenactis thompsonii

Key

1	Leaves ± cauline and, often, basal; plants not or scarcely cespitose, not matted; heads (1–)2–25+ per stem	> 2
1	Leaves ± basal; plants cespitose or ± matted; heads 1(–3) per stem	> 5
2	Subshrubs (usually); proximal indument (especially stems) persistent, whitish, densely lanuginose or pannose; largest leaf blades deltate to ovate, ± plane (California)	> 3
2	Biennials or perennials (rarely slightly woody or flowering first year); proximal indument ± thinning with age, grayish, arachnoid to ± lanuginose; largest leaf blades ± elliptic or lanceolate to ovate, plane or ± 3-dimensional	> 4
3	Phyllaries: longest 10–13 mm, outer predominantly arachnoid to closely lanuginose (sparsely, if at all, stipitate-glandular)	Chaenactis parishii
3	Phyllaries: longest 14–18 mm, outer predominantly stipitate-glandular (other indument none or sparse)	Chaenactis suffrutescens
4	Outer phyllaries usually densely, sometimes sparsely or obscurely, stipitate-glandular and, often, arachnoid, lanuginose, and/or villous; largest leaf blades ± 3-dimensional, usually 2-pinnately lobed, primary lobes ± congested, ultimate lobes ± involute and/or twisted	Chaenactis douglasii
4	Outer phyllaries closely lanuginose, not stipitate-glandular; largest leaf blades ± plane, 1-pinnately lobed, lobes remote, ± plane (Washington)	Chaenactis thompsonii
5	Outer phyllaries predominantly arachnoid, sericeous, or ± lanuginose (sparsely, if at all, stipitate-glandular)	> 6
5	Outer phyllaries predominantly or evidently stipitate-glandular (other indument none, sparse, or ± arachnoid)	> 8
6	Cypselae sparsely glandular amidst other indument; largest leaf blades 2-pinnately lobed (± 3-dimensional, primary lobes 4–12 pairs, peduncles mostly ascending to erect)	Chaenactis douglasii
6	Cypselae eglandular; largest leaf blades (0–)1(–2)-pinnately or -subpalmately lobed (± plane, and/or primary lobes 0–4 pairs, and/or peduncles mostly prostrate)	> 7
7	Longest pappus scales 2.5–4.5 mm (lengths 0.4–0.8 times corollas); leaf blades ± plane; peduncles mostly ascending to erect; Idaho	Chaenactis evermannii
7	Longest pappus scales 5–8 mm (lengths 0.9–1 times corollas); leaf blades ± plane or 3-dimensional; peduncles mostly prostrate; California, Nevada	Chaenactis alpigena
8	Largest leaf blades deltate to ovate, ± plane, ultimate lobes ± plane	> 9
8	Largest leaf blades linear-cylindric to ± elliptic or slightly ovate, ± 3-dimensional, ultimate lobes ± involute and/or twisted	> 10
9	Plants 2–10(–12) cm; leaves 2.5–5 cm; longest phyllaries 9–12(–14) mm; corol-las 5.5–8 mm; longest pappus scales 3–5 mm	Chaenactis nevadensis
9	Plants (10–)25–45(–60) cm; leaves 5–10 cm; longest phyllaries 14–18 mm; corollas 8.5–10 mm; longest pappus scales 7–9 mm	Chaenactis suffrutescens
10	Largest leaf blades ± elliptic to slightly ovate, primary lobes (4–)5–9(–12) pairs, ± congested, scarcely imbricate; not s California	Chaenactis douglasii
10	Largest leaf blades linear-cylindric to ± fusiform, primary lobes (7–)10–18+ pairs, ± imbricate; s California	Chaenactis santolinoides