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rush bristleweed, rush-like bristleweed

goldenweed, gumweed aster, rayless tansyaster

Habit Subshrubs, 25–100 cm; caudices branched, taproots 2–10+ cm. Subshrubs, 3–35 cm (tufted or densely cespitose, often mound-forming); caudices much branched, taproot 2–20+ cm.
Stems

3–15+, branched in distal 1/2, slender and wiry, glabrous.

10–30+, simple or branched in distal 1/3, moderately stout to stout, not wiry, hairy or minutely stipitate-glandular.

Leaves

basal often withering by flowering, 20–35 × 6–12 mm, pinnatifid;

cauline evenly spaced, blades oblong to linear, scalelike, 4–6 × 1–2 mm (except proximalmost), markedly reduced distally, margins usually entire, faces glabrous.

basal often persistent;

cauline evenly spaced, blades oblong, obovate, lanceolate to spatulate or narrowly ovate to obovate, 7–60 × 2–13 mm, gradually reduced distally, margins usually evenly coarsely serrate to serrulate, teeth 4–16 per side, each tipped with white bristle 0.5–4 mm, faces sparsely to densely hairy (hairs subappressed), often minutely stipitate-glandular.

Peduncles

minutely glandular, if stipitate, then minutely so;

bracts 5–25, imbricate, grading into phyllaries.

sparsely to densely hairy, often stipitate-glandular;

sometimes bracteate.

Involucres

hemispheric (narrowed at bases), 0.5–0.8 × 1–1.2 cm.

hemispheric to campanulate, 0.5–1 × 0.6–1.5 cm.

Ray florets

15–25;

corollas yellow, tubes 3.5–4 mm, laminae 5–6 × 1.5–2.5 mm.

0.

Disc florets

25–40+;

corollas 4.8–6.3 mm.

15–50+;

corollas 5–8.5 mm.

Phyllaries

in 5–6 series, oblong to linear-oblanceolate, 1.5–6.5 mm, apices acute, tipped by white bristle, faces minutely stipitate-glandular.

in 3–5 series, oblong to broadly lanceolate, 2–9 mm, apices obtuse to acute, tipped by white seta, faces usually densely stipitate-glandular.

Heads

1–10+.

Cypselae

narrowly obovoid to oblanceoloid, 1.5–2.5 mm, nerves 12–18, moderately tawny hairy;

pappi tawny, 3.5–6 mm, a few abaxial bristles to 1/3 of longest.

oblong to narrowly obovoid, 2–3.5 mm, ribs 12–24, densely whitish to tawny hairy;

pappi whitish to tawny, 3–7 mm, a few abaxial bristles to 1/3 of longest.

2n

= 8, 16.

Xanthisma junceum

Xanthisma grindelioides

Phenology Flowering summer–fall.
Habitat Rocky, dry slopes
Elevation 100–1000 m (300–3300 ft)
Distribution
from FNA
CA; Mexico (Baja California, Sonora)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CO; ID; MT; ND; NE; NM; NV; SD; UT; WY; AB; SK
[WildflowerSearch map]
[BONAP county map]
Discussion

Xanthisma junceum is reported from Arizona, but no specimen has been seen; as it is coastal in distribution, the report is likely based on a misidentified specimen.

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

Varieties 2 (2 in the flora).

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

Key
1. Plants tufted, 10–35 cm; leaves evenly distributed along stems, margins usually ciliate, sometimes spinulose-dentate, bristles usually 0.5–1.5 mm; heads 1 or often 2–5; peduncles 0.5–2 cm, often bracteate to proximal to heads
var. grindeloides
1. Plants densely cespitose, mostly 3–8 cm; leaves mostly crowded at base of stem, margins conspicuously white-bristled (1.5–)2–4 mm; heads usually 1; peduncles 1–4 cm, usually ebracteate
var. depressum
Source FNA vol. 20, p. 390. FNA vol. 20, p. 387.
Parent taxa Asteraceae > tribe Astereae > Xanthisma > sect. Sideranthus Asteraceae > tribe Astereae > Xanthisma > sect. Blepharodon
Sibling taxa
X. blephariphyllum, X. coloradoense, X. gracile, X. grindelioides, X. gypsophilum, X. spinulosum, X. texanum, X. viscidum
X. blephariphyllum, X. coloradoense, X. gracile, X. gypsophilum, X. junceum, X. spinulosum, X. texanum, X. viscidum
Subordinate taxa
X. grindelioides var. depressum, X. grindelioides var. grindeloides
Synonyms Haplopappus junceus, Machaeranthera juncea Eriocarpum grindelioides, Haplopappus nuttallii, Machaeranthera grindelioides
Name authority (Greene) D. R. Morgan & R. L. Hartman: Sida 20: 1406. (2003) (Nuttall) D. R. Morgan & R. L. Hartman: Sida 20: 1403. (2003)
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