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FNA | Family List | FNA Vol. 5 | Polygonaceae

12. Chorizanthe R. Brown ex Bentham, Trans. Linn. Soc. London. 17: 416, plate 17, fig. 11; plate 19. 1836.

Spineflower [Greek chorizo, to divide, and anthos, flower, alluding to tepals]

James L. Reveal

Herbs [or subshrubs], annual [or perennial]; taproot slender to stout. Stems prostrate or decumbent to erect, pubescent; aerial flowering stems arising [at nodes of caudex branches, at distal nodes of aerial stems or] directly from the root, decumbent to erect, slender [to stout and solid, not disarticulating in ringlike segments], sometimes disarticulating at each node. Leaves persistent or quickly deciduous, basal and rosulate or basal and cauline, alternate; petiole present; blade linear to oblanceolate or spatulate, entire apically. Inflorescences terminal, cymose or capitate, uniparous due to suppression of secondaries; branches open and spreading or erect, typically trichotomously branched at proximal node, otherwise dichotomous, sometimes brittle and disarticulating into segments, round, pubescent [or rarely glabrous]; bracts mostly 2, opposite, sometimes numerous, whorled, distinct, leaflike to subulate or linear, occasionally awn-tipped, thinly pubescent (sometimes appressed), hirsute, villous, strigose, or tomentose, rarely woolly-floccose or minutely glandular. Peduncles absent. Involucres 1-6+ per node, 3-6-ribbed, tubular, cylindric to urceolate or turbinate to campanulate; teeth 3, 5, or 6, awn-tipped. Flowers bisexual, 1(-2) per involucre, pedicellate; perianth white to yellow or pink to rose-pink, red, maroon or purple, cylindric, funnelform, or campanulate when open, cylindric when closed, glabrous or pubescent abaxially; tepals (5-)6, connate 3 their length, monomorphic or dimorphic, entire, emarginate, or lobed to laciniate apically; stamens 3, 6, or 9, or variously 3-9; filaments distinct or connate into staminal tube, sometimes adnate to floral tube, glabrous or pubescent; anthers maroon to red or cream to white or yellow, oval to oblong; styles erect to spreading. Achenes included, light brown to dark brown or black, not winged, lenticular, globose-lenticular, or 3-gonous, glabrous. Seeds: embryo straight or curved. x = 10.

Species 50 (33 in the flora): North America (including Mexico), South America.

Like Eriogonum, Chorizanthe is the basal element in its own subtribe, Chorizanthineae Reveal. Nonetheless, recent molecular data indicate that Chorizanthe is embedded within Eriogonum (A. S. Lamb Frye, pers. comm.), meaning that either all species of the Chorizanthineae should be moved to Eriogonum, or Eriogonum should be fragmented into several genera. Obviously, therefore, all of the segregate genera that follow could be merged into Chorizanthe, and this was common practice until 1989. A key factor still unresolved is the relationship between the perennial species of Chorizanthe (including the type of the genus) and Eriogonum. The traditional assumption is that Eriogonum and Chorizanthe represent independent lines of evolution from a basal, diploid (n = 10) ancestor that is now extinct. A corollary to this assumption is that this divergence occurred during the Eocene and the perennial spineflowers were successfully introduced into southern South America, whereas the wild buckwheats—lacking a ready means for long-distance dispersal—failed to make the trip. Thus, it is possible that the perennial members of Chorizanthe represent a genus distinct from the annuals treated here (33 of the 41 annuals occur in the flora area, the rest are in Mexico or in South America). In that case, our annual members (if not submerged into Eriogonum) would be called Acanthogonum Torrey.

The segregate genera allied to Chorizanthe, like those allied to Eriogonum, differ primarily in their involucres. Aristocapsa and Dodecahema, with haploid chromosome numbers of 14 and 17, respectively, are difficult to associate with any extant member of Chorizanthe (mainly n = 19, 20, 38, 40). Centrostegia, Lastarriaea, Mucronea, and Systenotheca all appear much more akin to Chorizanthe. A point of origin can be suggested only for Lastarriaea, namely Chorizanthe interposita Goodman of central Baja California, Mexico. C. D. Hardham (1989) reported a range of gametic numbers from single individuals. Until somatic counts are made, the primary chromosome numbers of some species remain uncertain.

J. L. Reveal and C. B. Hardham (1989b) divided the annual species of Chorizanthe genus into three subgenera: subg. Amphietes (39 species), and subg. Eriogonella and subg. Quintaria (one species each). The first is divided into four sections (Ptelosepala, Acanthogonum, Fragile, and Clastoscapa Reveal & Hardham), all but the last of which are found in our region. Some sections were divided into subsections, which are not treated here.

The approximately nine perennial species of subg. Chorizanthe occur only in arid regions of Chile and Argentina.


Goodman, G. J. 1934. A revision of the North American species of the genus Chorizanthe. Ann. Missouri Bot. Gard. 21: 1-102. Reveal, J. L. and C. B. Hardham. 1989b. A revision of the annual species of Chorizanthe (Polygonaceae: Eriogonoideae). Phytologia 66: 98-198.

1 Involucres 3-5-toothed or 3-5-ribbed   (2)
+ Involucres 6-toothed (teeth sometimes vestigial or 6-ribbed)   (7)
2 (1) Involucral teeth (4-)5   (3)
+ Involucral teeth 3   (5)
3 (2) Involucral awns straight; perianths glabrous; filaments adnate at base of tepals; deserts, s California   1 Chorizanthe spinosa
+ Involucral awns uncinate; perianths pubescent abaxially; filaments adnate near top of floral tube; mountains, coastal mesas, deserts, w North America   (4)
4 (3) Involucres campanulate, 1.5-2.5 mm, anterior tooth not leaflike; perianths white to rose, densely pubescent abaxially, 1.5-1.8(-2) mm; mountains and coastal mesas of California   28 Chorizanthe polygonoides (in part)
+ Involucres cylindric, 3-4.5 mm, anterior tooth leaflike; perianths yellow, thinly pubescent abaxially, 1.5-2.5 mm; deserts of w North America   31 Chorizanthe watsonii
5 (2) Involucres cylindric, markedly transversely corrugate; perianths thinly pubescent abaxially; stamens 6   32 Chorizanthe corrugata
+ Involucres urceolate to campanulate; perianths densely pubescent abaxially; stamens 9   (6)
6 (5) Plants erect; involucres urceolate, anterior tooth 5-10 mm with straight awn; achenes 3-gonous; warm deserts of sw North America   29 Chorizanthe rigida
+ Plants prostrate; involucres campanulate, anterior tooth 1.8-2 mm with uncinate awn; achenes lenticular; coastal mesas of extreme sw California   30 Chorizanthe orcuttiana
7 (1) Involucral teeth with scarious or membranous margins   (8)
+ Involucral teeth without scarious or membranous margins   (19)
8 (7) Involucral teeth margins membranous, continuous across sinuses   (9)
+ Involucral teeth margins scarious, parted or divided at sinuses, sometimes with distinct margin between erect teeth   (12)
9 (8) Tepals obcordate to 2-lobed apically   (10)
+ Tepals entire apically   (11)
10 (9) Tepals not denticulate apically; n, c California   3 Chorizanthe stellulata (in part)
+ Tepals denticulate apically; wc California   4 Chorizanthe douglasii (in part)
11 (9) Involucres tomentose to floccose or glabrate, 3-4 mm; perianths densely pubescent abaxially, (1.5-)2.5-3 mm; sc Oregon and California   2 Chorizanthe membranacea
+ Involucres sparsely pubescent and hispid at least along ridges, 3-5 mm; perianths slightly pubescent abaxially, 3.5-4(-4.5) mm; wc California   4 Chorizanthe douglasii
12 (8) Involucral awns straight   (13)
+ Involucral awns uncinate   (15)
13 (12) Involucres congested in small bracteated clusters; leaf blades hirsute; tepals monomorphic; Coast Ranges of California   3 Chorizanthe stellulata (in part)
+ Involucres 1; leaf blades villous; tepals dimorphic; coastal dunes and grasslands of California   (14)
14 (13) Perianths (3-)3.5-4.5 mm, pubescent nearly throughout; plants spreading or decumbent to somewhat erect   10 Chorizanthe howellii
+ Perianths (4-)5-6 mm, hairy on proximal 2; plants erect to spreading   11 Chorizanthe valida (in part)
15 (12) Perianths glabrous; tepals entire apically; floral tubes lemon-yellow; coastal California   5 Chorizanthe diffusa
+ Perianths pubescent abaxially; floral tubes white   (16)
16 (15) Involucres 2.5-4 mm, thinly pubescent abaxially; perianths 2.5-4 mm; wc California   9 Chorizanthe robusta
+ Involucres 1.5-2.5(-3) mm, villous abaxially; perianths 2-3 mm; coastal California   (17)
17 (16) Tepals cuspidate apically   8 Chorizanthe cuspidata (in part)
+ Tepals erose apically   (18)
18 (17) Involucral margins white to pink or purple; involucres 2-2.5(-3) mm; perianths 2-3.5 mm; stamens 9   6 Chorizanthe pungens
+ Involucral margins pinkish; involucres 1.5-2(-2.5) mm; perianths 2-3 mm; stamens 3 or 6-9   7 Chorizanthe angustifolia (in part)
19 (7) Involucral awns unequal, anterior one greatly elongated   (20)
+ Involucral teeth of equal or alternating lengths but anterior tooth not greatly elongated   (22)
20 (19) Anterior awns uncinate; c and n California   18 Chorizanthe clevelandii
+ Anterior awns straight; c California   (21)
21 (20) Outer tepals obovate to nearly orbiculate, 2-lobed apically; inner tepals erose apically; stamens 9; Coast Ranges, c California   17 Chorizanthe rectispina
+ Outer tepals narrowly oblong, with minute cusp or 3 teeth apically; inner tepals entire apically; stamens 3; Coast Ranges, Transverse Ranges, Tehachapi Ranges, s Sierra Nevada, c California   19 Chorizanthe uniaristata
22 (19) Tepals all, or at least inner ones, fimbriate or 2-lobed apically   (23)
+ Tepals entire, cuspidate, or erose apically   (28)
23 (22) Outer and inner tepals fimbriate to laciniate apically; montane s California   27 Chorizanthe fimbriata
+ Outer tepals entire or if fimbriate to variously divided then inner tepals not fimbriate to laciniate; coastal ranges of California   (24)
24 (23) Tepals white to pinkish   (25)
+ Tepals red, maroon, or dark purple   (26)
25 (24) Inner tepals fimbriate apically   15 Chorizanthe obovata
+ Inner tepals 2-lobed apically   16 Chorizanthe blakleyi
26 (24) Outer tepals entire, erect; involucres 3.5-4 mm; involucral awns 0.5-1 mm   12 Chorizanthe palmeri
+ Outer tepals shallowly lobed, obcordate, 2-lobed, erose, or at least wavy apically, spreading to recurved; involucres 4-6 mm; involucral awns 0.5-2 mm   (27)
27 (26) Outer tepals 2-lobed or obcordate apically; inner tepals fimbriate apically; perianths (4.5-)5-6 mm; involucres 4-6 mm, slightly ventricose basally   13 Chorizanthe biloba
+ Outer tepals erose or at least wavy apically; inner tepals fimbriate or somewhat 2-lobed apically; perianths 4-4.5 mm; involucres 4-4.5 mm, strongly ventricose basally   14 Chorizanthe ventricosa
28 (22) Tepals monomorphic   (29)
+ Tepals dimorphic, sometimes monomorphic, inner ones usually narrower and shorter than outer ones   (33)
29 (28) Plants spreading to erect; stems disarticulating at nodes; stamens 3; filaments adnate at top of floral tube   33 Chorizanthe brevicornu
+ Plants prostrate or decumbent to ascending or erect; stems not disarticulating at nodes; stamens 3 or 6-9 and filaments adnate at base of floral tube or stamens 6 or 9 and filaments adnate at top of floral tube   (30)
30 (29) Filaments adnate at top of floral tube; tepals obtuse to truncate or minutely emarginate apically; achenes 3-gonous; mountains and coastal mesas of California   28 Chorizanthe polygonoides (in part)
+ Filaments adnate at base of floral tube; tepals entire, erose, or cuspidate apically; achenes lenticular or globose-lenticular; sw and wc California   (31)
31 (30) Tepals entire apically; filaments connate basally; sw California   21 Chorizanthe procumbens
+ Tepals erose or cuspidate apically; filaments distinct; coastal c California   (32)
32 (31) Tepals erose apically; flowers slightly exserted   7 Chorizanthe angustifolia (in part)
+ Tepals cuspidate apically; flowers included to slightly exserted   8 Chorizanthe cuspidata (in part)
33 (28) Involucral awns straight; tepals erose to denticulate   (34)
+ Involucral awns uncinate; tepals entire or denticulate   (35)
34 (33) Plants erect to spreading; involucres 3-4(-4.5) mm; wc California   11 Chorizanthe valida (in part)
+ Plants prostrate to spreading; involucres 1.5-2 mm; sw California   20 Chorizanthe parryi (in part)
35 (33) Involucres 1.5-2 mm; s California   20 Chorizanthe parryi (in part)
+ Involucres 2-6 mm; California   (36)
36 (35) Proximal leaflike bracts soon deciduous or absent   (37)
+ Proximal leaflike bracts persistent   (38)
37 (36) Perianths 3-4(-5) mm; flowers mostly included; involucres usually congested terminally; coastal to montane sw California   22 Chorizanthe staticoides
+ Perianths 4.5-6 mm; flowers long-exserted; involucres 1; montane s California   23 Chorizanthe leptotheca
38 (36) Perianths 4.5-6 mm; flowers long-exserted; inland California   24 Chorizanthe xanti
+ Perianths 2.5-3.5 mm; flowers exserted; coastal and insular sw California   (39)
39 (38) Perianths 3-3.5 mm; involucres 2.5-3 mm, hairs slender, curly; stamens 9; coastal sw California   25 Chorizanthe breweri
+ Perianths 2.5-3 mm; involucres 2-2.5 mm, hairs stoutish, recurved; stamens 6; insular sw California   26 Chorizanthe wheeleri

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