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riverside spineflower, Xantus' spineflower

Douglas' spineflower, San Benito spineflower

Habit Plants erect to infrequently spreading, (0.3–)0.5–2.5(–3) × 0.5–3(–5) dm, thinly pubescent. Plants erect, 1–4(–5) × 0.5–3 dm, villous.
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(–6) cm;

blade oblanceolate, 0.5–2(–4) × 0.1–0.4(–1) cm, villous.

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.

cymose, dichotomously branched throughout, white to greenish or reddish;

bracts usually 2, similar to proximal leaf blades, typically with whorl of 3–5 ca. midstem, short-petiolate, becoming linear and aciculate at distal nodes, acerose, 0.5–2(–3) cm × 1–5(–10) mm, awns absent.

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.

congested in small leafy terminal clusters of 2–4 at nodes of dichotomies, greenish, cylindric, slightly ventricose basally, 3–5 mm, with conspicuous, purple, broad, membranous margins typically extending across sinuses, finely corrugated, hispid at least along ridges, otherwise sparsely pubescent;

teeth spreading, equal, (0.7–)1–1.5 mm, awns straight, 0.5–1 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, cylindric, 3.5–4(–4.5) mm, slightly pubescent abaxially;

tepals connate 2/3 their length, monomorphic, obovate, 2-lobed or denticulate apically, infrequently inner whorl entire;

stamens 9, slightly exserted;

filaments distinct, 3–4 mm, glabrous;

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

Achenes

brown, lenticular, 4–4.5 mm.

light brown, globose-lenticular, 3.5–4 mm.

2n

= 40.

Chorizanthe xanti

Chorizanthe douglasii

Phenology Flowering Apr–Jul.
Habitat Sandy to gravelly flats and slopes, mixed grassland communities, oak and pine woodlands
Elevation (200-)300-1600 m ((700-)1000-5200 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.)

Chorizanthe douglasii is restricted to the Santa Lucia Mountains and to the San Gabilan and La Panza ranges of west-central California. The species is infrequent but can be locally common. A single collection made in the Santa Cruz Mountains (Rowntree s.n., 16 Jun 1929, CAS) may have been made in Santa Cruz County, but the location is uncertain and no other collection is known from that region.

(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. 452.
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. 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
Synonyms C. nortonii
Name authority S. Watson: Proc. Amer. Acad. Arts 12: 272. (1877) Bentham: Trans. Linn. Soc. London 17: 418. (1836)
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