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Mojave spineflower

Orcutt spineflower, Orcutt's spineflower, San Diego spineflower

Habit Plants spreading to prostrate, 0.3–0.8(–1) × 0.5–8 dm. Plants prostrate, 0.1–0.5 × 0.3–2(–2.5) dm, villous.
Leaves

basal;

petiole 0.5–2 cm;

blade (0.3–)0.5–1.5(–2) × (3–)5–10(–12) mm, thinly pubescent adaxially, more densely so to tomentose abaxially.

basal;

petiole 1–2 cm;

blade narrowly oblanceolate, 0.5–1.5 × 0.2–0.35(–0.5) cm, thinly pubescent.

Inflorescences

greenish to reddish, mostly flat-topped and open to dense;

bracts 3, whorled, short-petiolate, linear-lanceolate to lanceolate, acerose, 0.5–1.5 cm × 3–8(–10) mm, awns straight, 1–3.5 mm.

with involucres in small clusters 0.5–1 cm diam., greenish;

bracts 2, sessile, unequal, 1 laminar and oblanceolate, 0.3–1 cm × 1–3 mm, awnless, this opposite linear, acicular, greatly reduced, 0.1–0.2 cm × 0.3–0.6 mm bract terminated by short, straight awn 0.6–1 mm.

Involucres

usually congested in small terminal clusters of 1–3 at node of dichotomies, (4–)5-ribbed, weakly 3-angled, 2–2.5 mm, not corrugate, densely canescent;

teeth (4–)5, essentially erect with longer, prominent, and thickened anterior one 2–4 mm, with straight awn 1–2.5 mm, remaining teeth smaller, 0.5–1 mm, with straight awns 0.3–0.8 mm.

1, greenish, campanulate, 3-ribbed, 0.8–2 mm, faintly corrugate, pubescent;

teeth 3, equal, 1.8–2 mm;

awns uncinate, 0.6–1 mm.

Flowers

1, exserted;

perianth, cylindric, 2.5–3.5 mm;

tepals connate 1/2–2/3 their length, dimorphic, entire, those of outer whorl spreading, broadly obovate and rounded apically, those of inner whorl erect, narrowly oblanceolate, 1/2 length of outer ones, acute apically;

stamens slightly exserted;

filaments 2.5–3 mm, glabrous;

anthers yellowish, oblong, 0.5–0.7 mm.

1, included to slightly exserted;

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

tepals connate ca. 1/2 their length, monomorphic, narrowly oblanceolate, obtuse to truncate, entire apically, slightly spreading;

stamens 9, slightly exserted;

filaments distinct, 0.5–0.8 mm, glabrous;

anthers reddish, ovate, 0.2–0.3 mm.

Achenes

2.5–3 mm.

dark brown, lenticular, 2–2.2 mm.

2n

= (40), 44, (46).

= (76, 78), 80, (84).

Chorizanthe spinosa

Chorizanthe orcuttiana

Phenology Flowering Apr–Jul. Flowering Mar–May.
Habitat Sandy to gravelly flats and slopes, saltbush communities Sandy soil, mesas and hills near coast, coastal scrub communities
Elevation 600-1300 m (2000-4300 ft) 60-200 m (200-700 ft)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

G. J. Goodman (1934) referred Chorizanthe spinosa to Eriogonella, but C. spinosa and C. membranacea, the type of Eriogonella, are well isolated from one another, and both are well removed from the remainder of the annual spineflowers. The Mojave spineflower is local and uncommon from southeastern Kern and southern Inyo counties, south into adjacent northeastern Los Angeles and northwestern San Bernardino counties to Antelope and Lucerne valleys.

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

Of conservation concern.

Chorizanthe orcuttiana is known from a few populations on coastal mesas and hills near San Diego, San Diego County. It is federally listed as endangered. The species is an octoploid that may well have resulted from an ancient hybridization and doubling of chromosomes involving C. procumbens and C. polygonoides var. longispina. The Orcutt spineflower grows in soft, white sand; C. procumbens and C. polygonoides var. longispina are restricted to gravelly sites.

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

Source FNA vol. 5, p. 449. FNA vol. 5, p. 467.
Parent taxa Polygonaceae > subfam. Eriogonoideae > Chorizanthe > subg. Quintaria Polygonaceae > subfam. Eriogonoideae > Chorizanthe > subg. Amphietes > sect. Acanthogonum
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. 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. cuspidata, C. diffusa, C. douglasii, C. fimbriata, C. howellii, C. leptotheca, C. membranacea, C. obovata, 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 Eriogonella spinosa
Name authority S. Watson: in W. H. Brewer et al., Bot. California 2: 481. (1880) Parry: Proc. Davenport Acad. Nat. Sci. 4: 54. (1884)
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