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riverside spineflower, Xantus' spineflower

Brewer's spineflower, San Luis obispo spineflower

Habit Plants erect to infrequently spreading, (0.3–)0.5–2.5(–3) × 0.5–3(–5) dm, thinly pubescent. Plants ascending to decumbent, (0.3–)0.5–1.5(–2) × 1–5(–7) dm, thinly pubescent.
Leaves

basal or nearly so;

petiole 1–2(–3) cm;

blade oblong or oblong-ovate to ovate, 0.3–1(–1.5) × 0.3–0.8(–1) cm, thinly pubescent adaxially, densely tomentose abaxially.

basal;

petiole 1–3 cm;

blade spatulate to ovate, 0.5–2 × 0.3–1.2(–1.5) cm, thinly pubescent to densely tomentose at least abaxially.

Inflorescences

mostly flat-topped and openly branched, usually reddish;

bracts persistent, 2, usually leaflike at proximal nodes and similar to proximal leaf blades only more reduced, short-petiolate, oblong-ovate to ovate, 0.3–0.8 cm × 2–6 mm, becoming sessile, reduced and scalelike at distal nodes, linear, acicular, often acerose, 0.1–0.4 cm × 0.5–1 mm, awns straight, 0.5–1 mm.

mostly flat-topped, open to rather densely branched, greenish to reddish;

bracts persistent, 2, usually leaflike at proximal nodes and similar to leaf blades, short-petiolate, oblong to ovate, 0.3–0.8 cm × 2–6 mm, becoming sessile, reduced and scalelike at distal nodes, linear, acicular, often acerose, 0.1–0.5 cm × 0.5–1 mm, awns straight, 0.5–1 mm.

Involucres

in open clusters with 1 at node of dichotomies, reddish, cylindric, not ventricose, 3–4.5 mm, not corrugate, without scarious or membranous margins, thinly to densely pubescent;

teeth spreading, unequal, 0.7–1.5 mm, 3 longer ones more erect than 3 shorter and less-prominent ones;

awns uncinate, 0.5–1 mm.

in open clusters with 1 at node of dichotomies, reddish, cylindric, not ventricose, 2.5–3 mm, corrugate, without scarious or membranous margins, thinly pubescent with slender curly hairs;

teeth spreading, unequal, 0.4–1.2 mm with 3 longer ones more erect than 3 shorter and less-prominent ones;

awns uncinate, 0.3–0.6 mm.

Flowers

long-exserted;

perianth rose to red, infrequently with white lobes, cylindric, 4.5–6 mm, pubescent;

tepals connate ca. 2/3 their length, monomorphic to slightly dimorphic, narrowly oblanceolate, rounded apically, those of outer whorl occasionally slightly broader and longer than those of inner whorl;

stamens 9, mostly included;

filaments distinct, 4–6 mm, glabrous;

anthers pink to red, oblong, 0.5–0.6 mm.

exserted;

perianth white to rose or red, usually with white lobes, cylindric, 3–3.5 mm, pubescent;

tepals connate ca. 1/2 their length, monomorphic to slightly dimorphic, narrowly oblong to obovate, rounded apically, those of outer whorl usually slightly broader and longer than those of inner whorl;

stamens 9, mostly included;

filaments distinct, 2.5–3 mm, glabrous;

anthers pink to red, oblong, 0.4–0.5 mm.

Achenes

brown, lenticular, 4–4.5 mm.

brown, lenticular, 2.5–3 mm.

2n

= 38.

Chorizanthe xanti

Chorizanthe breweri

Phenology Flowering Mar–Jul.
Habitat Gravelly or rocky places, serpentine outcrops, mixed grassland and chaparral communities, pine-oak woodlands
Elevation 60-800 m (200-2600 ft)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

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

Of conservation concern.

Chorizanthe breweri is found infrequently in the Coast Ranges of southwestern California.

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

Key
1. Involucres thinly pubescent
var. xanti
1. Involucres densely white-pubescent
var. leucotheca
Source FNA vol. 5, p. 463. FNA vol. 5, p. 464.
Parent taxa Polygonaceae > subfam. Eriogonoideae > Chorizanthe > subg. Amphietes > sect. Ptelosepala Polygonaceae > subfam. Eriogonoideae > Chorizanthe > subg. Amphietes > sect. Ptelosepala
Sibling taxa
C. angustifolia, C. biloba, C. blakleyi, C. brevicornu, C. breweri, C. clevelandii, C. corrugata, C. cuspidata, C. diffusa, C. douglasii, C. fimbriata, C. howellii, C. leptotheca, C. membranacea, C. obovata, C. orcuttiana, C. palmeri, C. parryi, C. polygonoides, C. procumbens, C. pungens, C. rectispina, C. rigida, C. robusta, C. spinosa, C. staticoides, C. stellulata, C. uniaristata, C. valida, C. ventricosa, C. watsonii, C. wheeleri
C. angustifolia, C. biloba, C. blakleyi, C. brevicornu, C. clevelandii, C. corrugata, C. cuspidata, C. diffusa, C. douglasii, C. fimbriata, C. howellii, C. leptotheca, C. membranacea, C. obovata, C. orcuttiana, C. palmeri, C. parryi, C. polygonoides, C. procumbens, C. pungens, C. rectispina, C. rigida, C. robusta, C. spinosa, C. staticoides, C. stellulata, C. uniaristata, C. valida, C. ventricosa, C. watsonii, C. wheeleri, C. xanti
Subordinate taxa
C. xanti var. leucotheca, C. xanti var. xanti
Name authority S. Watson: Proc. Amer. Acad. Arts 12: 272. (1877) S. Watson: Proc. Amer. Acad. Arts 12: 270. (1877)
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