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devil's spineflower, rigid spineflower, rigid spiny-herb, spiny-herb

San Francisco spineflower

Habit Plants erect, 0.2–0.8(–1.5) × 0.1–0.7(–1) dm, pubescent. Plants decumbent to prostrate or ascending, 0.5–2(–2.5) × 0.5–10 dm, villous.
Leaves

basal and cauline;

petiole 0.5–3(–4) cm;

basal blade broadly elliptic to obovate, 0.5–2.5 × (0.3–)0.5–2 cm, thinly pubescent adaxially, more densely so to tomentose abaxially;

proximal cauline leaf soon deciduous, 1, blade similar to basal leaf blades only 1–2(–2.5) × 0.5–1.5 cm, mucronate to awn-tipped, awn mostly 2–4 mm;

distal cauline leaf blade persistent, 1 per node, sessile, blade linear to linear-lanceolate, 0.1–1.5 × 0.05–0.15 cm, becoming hard and thornlike with age.

basal;

petiole (0.5–)1–3 cm;

blade oblanceolate, (0.5–)1–5 × (0.3–)0.4–0.7(–1) cm, villous.

Inflorescences

with involucres in dense clusters in axils of bracts, these on short shoots and each subtended by cauline leaves;

bracts 2, subopposite to opposite, linear, 0.5–1(–1.2) cm × 1–2 mm, awns straight, 2–4 mm.

rather dense with secondary branches suppressed, greenish to reddish;

bracts 2, similar to proximal leaf blades only reduced, short-petiolate, becoming narrowly elliptic to linear-lanceolate and aciculate at distal nodes, acerose, 0.5–5 cm × 2–7 mm, awns 0.5–1.2 mm.

Involucres

1, greenish, urceolate, 3-ribbed, 2–3 mm, corrugate, pubescent, rarely villous near base in some;

teeth 3, unequal, with thickened anterior tooth toward base, 5–10 mm, sometimes expanding and becoming lanceolate to narrowly elliptic, others 0.5–1.2 mm;

awns straight.

1, greenish, cylindric, often ventricose basally, 1–3 mm, without scarious margins or if so then white to pink, thin, and restricted to basal portions of teeth, corrugate, villous abaxially;

teeth spreading, equal, 0.5–2 mm;

awns uncinate or straight with longer ones 2–3 mm and anterior one mostly 2.5–3 mm, these alternating with shorter 1–1.5(–1.7) mm ones.

Flowers

1–2, included to slightly exserted;

perianth yellow, cylindric, 1.5–1.8 mm, densely pubescent abaxially;

tepals connate ca. 2/3 their length, monomorphic, oblong, rounded, entire apically;

stamens 9, slightly exserted;

filaments distinct, 0.5–1 mm, glabrous;

anthers yellowish, ovate, 0.2–0.3 mm.

included to slightly exserted;

perianth bicolored with floral tube white and tepals white to rose, cylindric, 2–3 mm, pubescent abaxially;

tepals connate less than 1/4 their length, monomorphic, oblong, truncate to 3-lobed and distinctly cuspidate apically;

stamens 9, slightly exserted;

filaments distinct, 2–3 mm, glabrous;

anthers cream to rose, narrowly oblong, 0.3–0.4 mm.

Achenes

brown, 3-gonous, (1.5–)1.8–2.2 mm.

light brown, globose-lenticular, 2–3 mm.

2n

= 38, 40.

Chorizanthe rigida

Chorizanthe cuspidata

Phenology Flowering Feb–Jun.
Habitat Sandy to gravelly or rocky flats and slopes, desert scrub
Elevation -60-1900 m. (-200-6200 ft.)
Distribution
from FNA
AZ; CA; NV; UT; Mexico (Baja California, Sonora)
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
Discussion

Anyone with the misfortune to step bare-footed on Chorizanthe rigida after the plant has dried instantly appreciates its common name. The species is widespread on the Mojave and Sonoran deserts but only occasionally is it locally abundant or weedy. It is found also along the Lahontan Trough in western Nevada, a well-known biogeographic extension route north of the Mojave Desert (J. L. Reveal 1980). The exceedingly compact and dense inflorescences with suppressed secondary branches result in a series of leaves and bracts that subtend a closely arranged series of bracteated and involucrated flowers.

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

Varieties 2 (2 in the flora).

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

Key
1. Involucral awns uncinate apically; San Francisco area
var. cuspidata
1. Involucral awns straight, rarely curved or with 1 awn uncinate; Marin and Sonoma counties
var. villosa
Source FNA vol. 5, p. 467. FNA vol. 5, p. 454.
Parent taxa Polygonaceae > subfam. Eriogonoideae > Chorizanthe > subg. Amphietes > sect. Acanthogonum 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. 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. breweri, C. clevelandii, C. corrugata, 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. cuspidata var. cuspidata, C. cuspidata var. villosa
Synonyms Acanthogonum rigidum C. pungens var. cuspidata
Name authority (Torrey) Torrey & A. Gray: Proc. Amer. Acad. Arts 8: 198. (1870) S. Watson: Proc. Amer. Acad. Arts 17: 379. (1882)
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