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riverside spineflower, Xantus' spineflower

prickly spineflower, straight-awn spineflower

Habit Plants erect to infrequently spreading, (0.3–)0.5–2.5(–3) × 0.5–3(–5) dm, thinly pubescent. Plants spreading to decumbent, 0.3–0.8(–1) × 0.5–4(–5) dm, appressed-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 0.5–2 cm;

blade oblanceolate to spatulate, 0.5–1.5(–2) × 0.2–0.6 cm, thinly pubescent.

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.

with involucres in small, open clusters 0.5–1.5 cm diam., greenish to grayish;

bracts 2, without whorl of sessile bracts about midstem, usually leaflike, oblanceolate to elliptic, 0.5–1.5 cm × 1.5–5 mm, gradually reduced and becoming scalelike at distal nodes, linear, aciculate, acerose, 0.3–0.8 cm × 1–2 mm, awns straight, 0.5–1.5 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.

3–10+, grayish to reddish, urceolate, slightly ventricose basally, 2–2.5(–3) mm, slightly corrugate, without scarious or membranous margins, densely pubescent;

teeth spreading, unequal, 1–2 mm;

awns straight or uncinate, unequal, with longer anterior one straight, mostly 1.5–2.5 mm, others 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 bicolored with floral tube yellow and tepals yellow or white, cylindric, 3.5–4 mm, sparsely pubescent;

tepals connate 1/2 their length, dimorphic, obovate, those of outer whorl white, obovate to nearly orbiculate, 3–4 times longer than those of inner whorl, , truncate to slightly 2-lobed apically, those of inner lobes erect, yellow, broadly obovate, truncate and erose apically;

stamens 9, included;

filaments distinct, 1–1.5 mm, glabrous;

anthers yellow to golden, oblong, 0.5–0.6 mm.

Achenes

brown, lenticular, 4–4.5 mm.

brown, globose-lenticular, 3–3.5 mm.

2n

= (36), 40, (44).

Chorizanthe xanti

Chorizanthe rectispina

Phenology Flowering May–Jul.
Habitat Sandy to gravelly flats and slopes, mixed grassland communities, pine-oak woodlands
Elevation 200-600 m (700-2000 ft)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

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

Of conservation concern.

Chorizanthe rectispina is infrequent and localized in the Coast Ranges of west-central 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. 460.
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. 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. 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) Goodman: Ann. Missouri Bot. Gard. 21: 72. (1934)
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