Flora of North America species comparison

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Chaenactis douglasii

Chaenactis thompsonii

chaenactis, Douglas' dusty maidens, Douglas' dustymaiden, hoary chaenactis, hoary false-yarrow, hoary pincushion
Chaenactis thompsonii

Thompson's pincushion
Habit 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. Perennials, 10–30 cm (not or scarcely cespitose, not matted); proximal indument thinning with age, grayish, arachnoid-sericeous to thinly lanuginose.
Stems

1–25+, erect to spreading.

mostly 5–15+, ascending to erect.
Leaves

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.

mostly cauline, 2–5 cm;

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

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

mostly ascending to erect, 1–10 cm.

ascending to erect, 2–5 cm.
Involucres

obconic to ± hemispheric.

± obconic.
Corollas

5–8 mm.

7–9 mm.
Phyllaries

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.

longest (10–)12–15 mm;

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

1–25+ per stem.

mostly 1–3 per stem.
Cypselae

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

pappi: longest scales 3–6 mm.

7–9 mm (eglandular);

pappi: longest scales 3.5–5 mm.

Chaenactis douglasii

Chaenactis thompsonii
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
AZ; CA; CO; ID; MT; ND; NM; NV; OR; SD; UT; WA; WY; AB; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
WA
[WildflowerSearch map]
[BONAP county map]
Discussion

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.)

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.)
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. 405. FNA vol. 21, p. 407.
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. evermannii, C. fremontii, C. glabriuscula, C. macrantha, C. nevadensis, C. nevii, C. parishii, C. santolinoides, C. stevioides, C. suffrutescens, C. thompsonii, C. xantiana
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
Subordinate taxa
C. douglasii var. alpina, C. douglasii var. douglasii
Synonyms Hymenopappus douglasii, Macrocarphus douglasii
Name authority (Hooker) Hooker & Arnott: Bot. Beechey Voy., 354. (1839) Cronquist: in C. L. Hitchcock et al., Vasc. Pl. Pacif. N.W. 5: 123, fig. [p. 125]. (1955)
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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