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diffuse spineflower

Brewer's spineflower, San Luis obispo spineflower

Habit Plants spreading, decumbent, prostrate, or rarely slightly erect, 0.3–1(–1.5) × 0.5–2(–10) dm, villous. Plants ascending to decumbent, (0.3–)0.5–1.5(–2) × 1–5(–7) dm, thinly pubescent.
Leaves

basal;

petiole 0.2–1.8(–2) cm;

blade oblanceolate, 0.3–2 × 0.1–0.4 cm, villous.

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

rather dense with secondary branches suppressed, white to greenish;

bracts 2, similar to leaf blades at proximal nodes only reduced, short-petiolate, becoming linear and aciculate at distal nodes, acerose, 0.3–2 cm × 1–4 mm, awns absent.

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

1, mostly greenish, cylindric, not ventricose, 2–2.5 mm, with thin to broad and then conspicuous white or pinkish to purple, scarious margins extending nearly full length of awn, not corrugate, villous-hirsute;

teeth spreading to divergent, equal, 0.5–1 mm, awns uncinate with longer ones 1–2 mm, anterior one mostly 2 mm, alternating with shorter (0.5–1 mm) ones.

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

exserted;

perianth bicolored with floral tube lemon-yellow and tepals white, campanulate, 2.5–3 mm, glabrous;

tepals connate ca. 1/3 their length, monomorphic, oblong, acute to obtuse and entire apically;

stamens 3–9, slightly exserted;

filaments distinct, 1.5–2 mm, glabrous;

anthers yellow, oval, 0.3–0.4 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

dark brown, globose-lenticular, 2–2.5 mm.

brown, lenticular, 2.5–3 mm.

2n

= 38, 40, 42.

= 38.

Chorizanthe diffusa

Chorizanthe breweri

Phenology Flowering Apr–Jul. Flowering Mar–Jul.
Habitat Sandy to gravelly flats and slopes, coastal scrub communities, pine-oak woodlands Gravelly or rocky places, serpentine outcrops, mixed grassland and chaparral communities, pine-oak woodlands
Elevation 30-800 m (100-2600 ft) 60-800 m (200-2600 ft)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
Discussion

The involucral margins of Chorizanthe diffusa vary greatly. In some individuals, the white margins are barely visible. Plants with the margins of the involucre are predominantly white have been designated var. nivea. A full gradation between the extremes may be observed in most populations, although in coastal sands var. nivea is often the dominant expression. Diffuse spineflower occurs near the coast and in the Coast Ranges of central California.

Chorizanthe diffusa has been shown to inhibit carcinogen-induced preneoplastic lesions in a mouse mammary-organ culture model. This inhibitory activity is known to correlate with cancer chemopreventive effects in full-term models of tumorigenesis (see H. S. Chung et al. 1999).

(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.)

Source FNA vol. 5, p. 452. 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. 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
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
Synonyms C. andersonii, C. diffusa var. nivea, C. nivea, C. pungens var. diffusa, C. pungens var. nivea
Name authority Bentham: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 14: 26. (1856) S. Watson: Proc. Amer. Acad. Arts 12: 270. (1877)
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