Flora of North America species comparison

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Chaenactis thompsonii

Chaenactis douglasii
Chaenactis thompsonii

Thompson's pincushion

chaenactis, Douglas' dusty maidens, Douglas' dustymaiden, hoary chaenactis, hoary false-yarrow, hoary pincushion
Habit Perennials, 10–30 cm (not or scarcely cespitose, not matted); proximal indument thinning with age, grayish, arachnoid-sericeous to thinly lanuginose. Biennials or perennials, (2–)5–50(–60) cm (rarely slightly woody or flowering first year, sometimes cespitose or ± matted); proximal indument thinning with age, grayish, mostly arachnoid-sericeous to thinly lanuginose.
Stems

mostly 5–15+, ascending to erect.

1–25+, erect to spreading.
Leaves

mostly cauline, 2–5 cm;

largest blades ± elliptic, ± plane, 1-pinnately lobed;

lobes mostly 2–5 pairs, remote, ± plane.

basal, or basal (sometimes withering) and ± cauline, (1–)2–12(–15) cm;

largest blades ± elliptic or slightly lanceolate to ovate, ± 3-dimensional, usually 2-pinnately lobed;

primary lobes (4–)5–9(–12) pairs, ± congested, scarcely imbricate, ultimate lobes ± involute and/or twisted.
Peduncles

ascending to erect, 2–5 cm.

mostly ascending to erect, 1–10 cm.
Involucres

± obconic.

obconic to ± hemispheric.
Corollas

7–9 mm.

5–8 mm.
Phyllaries

longest (10–)12–15 mm;

outer closely lanuginose, not stipitate-glandular, apices erect, ± rigid.

longest 9–15(–17) mm;

outer usually stipitate-glandular (sometimes sparsely or obscurely, rarely eglandular) and, often, arachnoid to lanuginose and, sometimes, sparsely villous, apices usually ± squarrose, pliant.
Heads

mostly 1–3 per stem.

1–25+ per stem.
Cypselae

7–9 mm (eglandular);

pappi: longest scales 3.5–5 mm.

5–8 mm (usually sparsely glandular amidst other indument);

pappi: longest scales 3–6 mm.

Chaenactis thompsonii

Chaenactis douglasii
Phenology Flowering Jun–Aug.
Habitat Rocky or gravelly serpentine slopes, scree, talus, openings in or above conifer forests
Elevation (900–)1200–2200 m ((3000–)3900–7200 ft)
Distribution
from FNA
WA
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; CO; ID; MT; ND; NM; NV; OR; SD; UT; WA; WY; AB; BC
[WildflowerSearch map]
[BONAP county map]
Discussion

Of conservation concern.

Chaenactis thompsonii appears to be sister to C. evermannii; it is known from the mountains of central and northwestern Washington. The similar habits of C. thompsonii and C. ramosa (= C. douglasii var. douglasii) appear to result from convergent evolution in the distinctive habitat of their type localities (Wenatchee Mountains), not from a close genetic relationship as suggested by Cronquist.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Varieties 2 (2 in the flora).

Chaenactis douglasii is widespread and variable (see discussion under var. douglasii).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Leaves basal (sometimes withering) and ± cauline; plants not or scarcely cespitose, not matted; stems usually 1–5(–12); heads (1–)2–25+ per stem
var. douglasii
1. Leaves strictly basal; plants cespitose or ± matted; stems (1–)10–25+; heads 1(–2) per stem
var. alpina
Source FNA vol. 21, p. 407. FNA vol. 21, p. 405.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Chaenactidinae > Chaenactis > sect. Macrocarphus Asteraceae > tribe Heliantheae > subtribe Chaenactidinae > Chaenactis > sect. Macrocarphus
Sibling taxa
C. alpigena, C. artemisiifolia, C. carphoclinia, C. cusickii, C. douglasii, C. evermannii, C. fremontii, C. glabriuscula, C. macrantha, C. nevadensis, C. nevii, C. parishii, C. santolinoides, C. stevioides, C. suffrutescens, C. xantiana
C. alpigena, C. artemisiifolia, C. carphoclinia, C. cusickii, C. evermannii, C. fremontii, C. glabriuscula, C. macrantha, C. nevadensis, C. nevii, C. parishii, C. santolinoides, C. stevioides, C. suffrutescens, C. thompsonii, C. xantiana
Subordinate taxa
C. douglasii var. alpina, C. douglasii var. douglasii
Synonyms Hymenopappus douglasii, Macrocarphus douglasii
Name authority Cronquist: in C. L. Hitchcock et al., Vasc. Pl. Pacif. N.W. 5: 123, fig. [p. 125]. (1955) (Hooker) Hooker & Arnott: Bot. Beechey Voy., 354. (1839)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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