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five-tooth spineflower, Watson's spineflower

two lobed spineflower, twolobe spineflower

Habit Plants spreading to erect, 0.2–1(–1.5) × 0.2–1(–1.5) dm, densely canescent-strigose. Plants erect or infrequently spreading, (0.5–)1–3(–4) × 1–3(–4) dm, pubescent.
Leaves

basal or nearly so;

petiole (0.5–)1–2.5(–3) cm;

blade oblanceolate, (0.3–)0.5–1.5(–2) × 0.2–0.4(–0.5) cm, thinly floccose to sparsely tomentose.

basal;

petiole 0.5–3 cm;

blade oblanceolate, 1–3(–5) × 0.4–1(–1.3) cm, thinly pubescent.

Inflorescences

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

bracts 2, with laminar ones oblanceolate, (0.5–)0.8–1.5(–2) cm × (1–)2–4 mm, those at distal nodes becoming sessile, reduced and scalelike, linear-lanceolate, acicular, awns slightly curved, 0.5–1 mm.

with involucres in open clusters 2–4(–6) cm diam., greenish or reddish to purplish;

bracts 2–3 at proximal node, usually leaflike, often with whorl of sessile bracts ca. midstem, elliptic, 0.5–1.5 cm × 2–6 mm, gradually becoming lanceolate to elliptic, 0.2–2 cm × 1.5–8 mm, at distal nodes scalelike, linear and aciculate, acerose, awns straight, 1–3 mm.

Involucres

1, green, cylindric, 5-ribbed, 3–4.5 mm, finely corrugate, pubescent;

teeth 5, erect, unequal, with leaflike, narrowly lanceolate, 2–6 mm anterior tooth, others linear, 1–2 mm;

awn uncinate, 0.4–0.8(–1) mm.

3–10 or more, grayish or reddish, urceolate and slightly ventricose basally, 4–6 mm, without scarious or membranous margins, slightly corrugate, strigose;

teeth erect to spreading, unequal, 1–2 mm;

awns mostly uncinate, 0.5–2 mm, with longer anterior one straight, mostly 2 mm.

Flowers

1, included to slightly exserted;

perianth yellow, cylindric, 1.5–2.5 mm, thinly pubescent abaxially;

tepals connate ca. 2/3 their length, monomorphic, oblong, acute, entire apically, mostly erect;

stamens 3 or 9, slightly exserted;

filaments distinct, 0.8–1 mm, glabrous;

anthers yellow, ovate, 0.2–0.3 mm.

exserted;

perianth bicolored with floral tube white to yellow and tepals red, maroon, or dark purple, cylindric, (4.5–)5–6 mm, sparsely pubescent;

tepals connate 1/2 their length, dimorphic, obovate, those of outer whorl spreading, slightly longer than those of inner whorl, 2-lobed, emarginate, or subacute apically, those of inner whorl erect, obtuse, fimbriate apically;

stamens 9, exserted;

filaments distinct, 4–5 mm, glabrous;

anthers yellow to golden, oblong, 1.2–1.8 mm.

Achenes

brown, lenticular, 2.5–3 mm.

brown, globose-lenticular, 4–4.5 mm.

2n

= (34, 36, 38), 40, (42, 44, 46).

Chorizanthe watsonii

Chorizanthe biloba

Phenology Flowering Apr–Aug.
Habitat Sandy to gravelly flats and slopes, mixed grassland, saltbush and sagebrush communities, pinyon-juniper woodlands
Elevation 300-2400 m (1000-7900 ft)
Distribution
from FNA
AZ; CA; ID; NV; OR; UT; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
Discussion

Chorizanthe watsonii is widely distributed in the cold desert of the Great Basin and in the northern part of the warmer Mojave Desert. Plants in the northern part of the range (especially on the Palouse Prairie of south-eastern Washington) usually have three stamens.

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

Varieties 2 (2 in the flora).

Unlike the serpentine species Chorizanthe palmeri and C. ventricosa, C. biloba occurs on gravelly or clayey soils. Those species and C. obovata can be quickly differentiated by carefully examining the colors, shapes, and modifications of the tepals. Immature specimens can be difficult to place, but a combination of geographic location and edaphic features can often enable accurate identification of even fragmentary material.

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

Key
1. Outer tepals deeply 2-lobed, occasionally erose apically
var. biloba
1. Outer tepals emarginate or subcordate apically
var. immemora
Source FNA vol. 5, p. 468. FNA vol. 5, p. 458.
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. rigida, C. robusta, C. spinosa, C. staticoides, C. stellulata, C. uniaristata, C. valida, C. ventricosa, C. wheeleri, C. xanti
C. angustifolia, 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. xanti
Subordinate taxa
C. biloba var. biloba, C. biloba var. immemora
Synonyms C. palmeri var. biloba
Name authority Torrey & A. Gray: Proc. Amer. Acad. Arts 8: 199. (1870) Goodman: Ann. Missouri Bot. Gard. 21: 73. (1934)
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