Chorizanthe rigida
Chorizanthe diffusa
devil's spineflower, rigid spineflower, rigid spiny-herb, spiny-herb
diffuse spineflower
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 0.2–1.8(–2) cm;
blade oblanceolate, 0.3–2 × 0.1–0.4 cm, villous.
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, 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.
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, 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.
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.
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.
brown, 3-gonous, (1.5–)1.8–2.2 mm.
dark brown, globose-lenticular, 2–2.5 mm.
= 38, 40.
= 38, 40, 42.
Chorizanthe rigida
Chorizanthe diffusa
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.)
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.)
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