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centrostegia, red triangles

Habit Herbs, annual; taproot slender.
Stems

arising directly from the root, erect to spreading, solid, not fistulose or disarticulating into ringlike segments, sparsely glandular.

Leaves

usually quickly deciduous, basal, rosulate;

petiole present;

blade oblong to broadly spatulate, margins entire.

Inflorescences

terminal, cymose, uniparous due to suppression of secondaries;

branches dichotomous, not brittle or disarticulating into segments, solid, sparsely glandular;

bracts 3, positioned to side of node, connate ca. 1/4 their length, linear to linear-lanceolate, commonly acerose, awned, sparsely glandular.

Peduncles

absent.

Involucres

1 per node, tubular, prismatic, 3-angled, 3-awned basally on saccate lobes;

teeth 5, awn-tipped, awns straight.

Flowers

2 per involucre;

perianth white to pink, campanulate when open, cylindric when closed, pubescent proximally abaxially;

tepals 6, connate proximally, monomorphic, 2-lobed apically;

stamens 9;

filaments free, glabrous;

anthers pink to red, oblong.

Achenes

mostly included, brown, not winged, 3-gonous, glabrous.

Seeds

embryo curved.

x

= 19.

Centrostegia

Distribution
from USDA
sw United States; nw Mexico
[BONAP county map]
Discussion

Species 1.

The involucres of Centrostegia are highly modified and unique within Chorizanthineae. First, the involucres have basal and terminal awns. Second, the tube of the involucre is composed of five connate bracts—as in other genera with tubular involucres—but here four bracts are connate their entire length as two pairs with each bract terminated by a short, flatteened, keeled, awned tooth. The fifth bract, positioned opposite the point of attachment on the branch, is terminated by a short, flattened, awned tooth that is equal in size to the others.

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

Source FNA vol. 5, p. 473. Author: James L. Reveal.
Parent taxa Polygonaceae > subfam. Eriogonoideae
Subordinate taxa
C. thurberi
Synonyms Chorizanthe section C.
Name authority A. Gray ex Bentham: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 14: 27. (1856)
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