Flora of North America species comparison

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Chaenactis thompsonii

Chaenactis xantiana
Chaenactis thompsonii

Thompson's pincushion

fleshcolor pincushion, fleshy pincushion, Xantus' chaenactis
Habit Perennials, 10–30 cm (not or scarcely cespitose, not matted); proximal indument thinning with age, grayish, arachnoid-sericeous to thinly lanuginose. Plants 10–40 cm; proximal indument grayish, sparsely arachnoid, early glabrescent (usually glabrous by flowering).
Stems

mostly 5–15+, ascending to erect.

mostly 1–5(–12);

branches proximal and/or distal.
Leaves

mostly cauline, 2–5 cm;

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

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

basal (withering) and cauline, (1–)2–6 cm;

largest blades linear or ± elliptic, ± plane or terete, ± succulent, 0–1-pinnately lobed;

lobes 1–2(–5) pairs, remote, ± terete.
Peduncles

ascending to erect, 2–5 cm.

1–5(–8) cm, glabrous (and ± expanded) distally.
Involucres

± obconic.

broadly obconic to campanulate.
Florets

corollas (diurnal) dirty-whitish to pinkish, 6–10 mm (± equal to cypsela lengths, anthers exserted);

peripheral corollas erect to ascending, actinomorphic, scarcely enlarged.
Corollas

7–9 mm.

Phyllaries

longest (10–)12–15 mm;

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

longest 10–18 mm (surpassed by florets);

outer distally tomentulose-puberulent in fruit (proximally glabrous, not stipitate-glandular), apices ± squarrose, blunt, pliant.
Heads

mostly 1–3 per stem.

mostly 1–5(–7) per stem.
Cypselae

7–9 mm (eglandular);

pappi: longest scales 3.5–5 mm.

5–9 mm;

pappi of 8 scales in 2, abruptly unequal series, longest scales 5–9 mm.
2n

= 14.

Chaenactis thompsonii

Chaenactis xantiana
Phenology Flowering Jun–Aug. Flowering late Mar–Jul.
Habitat Rocky or gravelly serpentine slopes, scree, talus, openings in or above conifer forests Open, deep, loose sandy (rarely gravelly) soils, arid and semiarid shrublands, chaparral
Elevation (900–)1200–2200 m [(3000–)3900–7200 ft] (100–)300–2500 m [(300–)1000–8200 ft]
Distribution
map from FNA
WA
[WildflowerSearch map]
[BONAP county map]
map from FNA
AZ; CA; NV; OR
[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.)
Parent taxa Asteraceae > tribe Heliantheae > subtribe Chaenactidinae > Chaenactis > sect. Macrocarphus Asteraceae > tribe Heliantheae > subtribe Chaenactidinae > Chaenactis > sect. Chaenactis
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. douglasii, C. evermannii, C. fremontii, C. glabriuscula, C. macrantha, C. nevadensis, C. nevii, C. parishii, C. santolinoides, C. stevioides, C. suffrutescens, C. thompsonii
Name authority Cronquist: in C. L. Hitchcock et al., Vasc. Pl. Pacif. N.W. 5: 123, fig. [p. 125]. (1955) A. Gray: Proc. Amer. Acad. Arts 6: 545. (1865)
Source FNA vol. 21, p. 407. Treatment author: James D. Morefield. FNA vol. 21, p. 410. Treatment author: James D. Morefield.
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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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