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rush bristleweed, rush-like bristleweed

Texas sleepy-daisy

Habit Subshrubs, 25–100 cm; caudices branched, taproots 2–10+ cm. Annuals, rarely biennials; taproots 2–10+ cm.
Stems

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

1–3, usually branched in distal 1/2, sometimes throughout, moderately stout to stout, not wiry, mostly glabrous.

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 (if persisting) 50–80 × 15–25 mm, pinnatifid, rarely 2-pinnatifid;

cauline evenly spaced, proximal often spatulate, distal 2/3 narrowly to broadly lanceolate, 5–35 × 8–12 mm, markedly reduced distally, margins of proximal pinnatifid to coarsely serrate, of distal minutely, evenly serrulate or entire and antrorsely ciliolate, teeth or cilia 50–90+ per side, teeth tipped by white seta 0.1–1.5 mm, faces glabrous.

Peduncles

minutely glandular, if stipitate, then minutely so;

bracts 5–25, imbricate, grading into phyllaries.

moderately to densely hispidulous, eglandular; usually ebracteate.

Involucres

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

hemispheric, 5–10 × 11–20 mm.

Ray florets

15–25;

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

12–34;

corollas yellow, tubes 2.5–3 mm, laminae 5–18 × 2–3 mm.

Disc florets

25–40+;

corollas 4.8–6.3 mm.

50–200+;

corollas 4.5–5 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 3–4 series, faces glabrous; outer usually 1.5–8.5 × 2–5 mm, ciliate; inner 2–10.5 × 1.5–4 mm, often ciliate.

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.

1.6–1.8 mm;

pappi 5–6.5 mm, outer lengths often 0.5 longest.

2n

= 8, 16.

Xanthisma junceum

Xanthisma texanum

Phenology Flowering summer–fall.
Habitat Rocky, dry slopes
Elevation 100–1000 m [300–3300 ft]
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 3 (3 in the flora).

The polymorphic Xanthisma texanum has always been kept distinct from other genera in the tribe, in part due to the unique involucre, here considered a derived structure. The relationship to members of Machaeranthera in the broad sense was never considered until DNA data became available. According to J. C. Semple (1974), the following combination of features characterizes the species: “heterocarpic fruit with a pappus of bristly scales only, fruit pubescence of long white ascending hairs, receptacle slightly convex with a persistent reticulate network of subulate scales.” Interestingly, all of these characters are found in at least some of the taxa of the newly expanded genus.

J. C. Semple (1974) classified varieties texanum and orientale under the typical subspecies (as they are peripherally sympatric and appear to hybridize) and the allopatric X. texanum var. drummondii at the subspecific level. The three taxa are here treated as varieties.

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

Distribution
from FNA
CA; Mexico (Baja California, Sonora)
[WildflowerSearch map]
[BONAP county map]
from FNA
OK; TX
[WildflowerSearch map]
[BONAP county map]
Parent taxa Asteraceae > tribe Astereae > Xanthisma > sect. Sideranthus Asteraceae > tribe Astereae > Xanthisma > sect. Xanthisma
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. grindelioides, X. gypsophilum, X. junceum, X. spinulosum, X. viscidum
Subordinate taxa
X. texanum var. drummondii, X. texanum var. orientale, X. texanum var. texanum
Key
1.Phyllaries abruptly expanded distal to stalks; bodies mostly ovate (3.5–8 × 2.5–5 mm distal to widest point)X. texanum var. drummondii
1.Phyllaries somewhat expanded distally; bodies mostly orbiculate to depressed-elliptic (1–2 × 1.5–3.5 mm distal to widest point)→ 2
2.Phyllary apices rounded, with little or no flare 1 mm from tipX. texanum var. texanum
2.Phyllary apices obtusely cuspidate, flareddistally, ovate portion 1.5–2 × 2–3 mm (distal to widest point)X. texanum var. orientale
Synonyms Haplopappus junceus, Machaeranthera juncea
Name authority (Greene) D. R. Morgan & R. L. Hartman: Sida 20: 1406. (2003) de Candolle: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 95. (1836)
Source Flora of North America vol. 20, p. 390. Flora of North America vol. 20, p. 385.
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