4 POLYGONACEAE 



6. CHORIZANTHE R. Br. ex Benth. Trans. Linn. Soc. 17: 416. pi. 19. 1836. 



Low dichotomously branched annual or perennial herbs, with rosulate basal leaves and 

 opposite or ternate stem leaves often reduced and bracteate. Involucres 1 -flowered or 

 rarely 2-3-flowered, cylindric or funnelform, sessile, 3-6-angled or -ribbed, 3-6-toothed, 

 the teeth divaricate, cuspidate or awned. Flowers pedicellate or subsessile, included within 

 the involucre or partly exserted; bractlets wanting; calyx 6-parted or -cleft, usually white 

 or pink. Stamens 9, rarely 3 or 6, adnate to the base of the calyx -tube. Achene glabrous, 

 3-angled ; cotyledons straight or accumbent. [Name Greek, meaning divide and flower in 

 reference to the divided calyx.] 



An American genus of about 50 species inhabiting arid southwestern United States, Mexico, and Chile. Most 

 of the South American species are perennial, whereas all of ours are annuals. Type species, Chorizanthe virgata 

 Benth. 



Bracts entire. 



Involucres 6-toothed and 6-ribbed. 



Teeth of the involucre not membranous on the margin. 



Involucral teeth nearly equal but the outer three often larger than the inner three. 

 Calyx-lobes entire or erose, but not fimbriate. 



Outer and inner calyx-lobes similar or the inner slightly smaller. 

 Plants erect; joints of the stem very fragile. 



Leaves narrowly oblanceolate, 2-3 mm. broad. 1. C. brevicornu. 



Leaves broadly spatulate, 8-1 S mm. broad. 2. C. spathulata. 



Plants procumbent or ascending; joints of the stem not noticeably fragile. 

 Involucral teeth uncinate. 



Calyx-lobes scarcely exceeding the involucral tube, not apiculate. 



Stamens 3. 3. C. angustifolia. 



Stamens 9. 4. C. procumbens. 



Calyx-lobes distinctly exserted beyond the involucral tube, and distinctly 

 apiculate. 5. C. cuspidata. 



Involucral teeth straight. 6. C. villosa. 



Outer and inner calyx-lobes dissimilar, the inner much shorter and narrower. 

 Teeth of the involucre uncinate or the tips recurved. 



Bracts not foliaceous, or those of the first node rarely so and then early deciduous. 

 Calyx 4 mm. or less in length, the lobes oblong. 7. C. staticoides. 

 Calyx 4.5-5 mm. long; outer lobes linear. 8. C. leptotheca. 



Bracts except the floral ones foliaceous, those of the stems and main branches 

 usually similar to the basal leaves. 

 Calyx 5-6 mm. long. 9. C. Xantii. 



Calyx 4 mm. or less in length. (See also vigorous forms of C. staticoides.) 

 Foliaceous bracts lanceolate. 



Head-like clusters of involucres 10-15 mm. broad. 



10. C. Wheeleri. 

 Head-like clusters of involucres less than 10 mm. broad. 



11. C. Parryi. 

 Foliaceous bracts mostly broadly ovate or obovate. 



12. C. Breweri. 



Teeth of the involucre straight, not recurved nor uncinate; calyx erose. 



Plants decumbent; involucral tube not wrinkled between the ribs, the teeth widely 

 divergent. 11. C. Parryi fernandina. 



Plants erect; involucral tube transversely wrinkled between the ribs, the teeth 



erect. 21. C. valida. 

 Calyx-lobes at least the inner three fimbriate. 



Outer calyx-lobes entire, the inner fimbriate. 13. C. Palmeri. 



Outer and inner calyx-lobes all fimbriate. 14. C. fimbriata. 



Involucral teeth very unequal, the anterior one usually longer than the tube, the other five short. 



Elongated anterior tooth straight. 15. C. uniaristata. 



Elongated anterior tooth uncinate. 16. C. Clevelandii. 



Teeth of the involucre with membranous often white or colored margins. 



Membranous margins not continuous through the sinuses but cleft or parted. 

 Involucral teeth uncinate or recurved at apex. 



Plants decumbent or prostrate; involucres 4 mm. or less in length. 



Calyx-lobes erose, the outer obovate or rarely oblong. 17. C. pungens. 

 Calyx-lobes not erose, the outer oblong to lanceolate. 



Lobes of the calyx cuspidate. 5. C. cuspidata. 



Lobes of the calyx entire not cuspidate. 18. C. diffusa. 

 Plants erect; involucres over 4 mm. long. 



Involucres hispid, margins white. 19. C. stellulata. 



Involucres hirsute, margins not white. 20. C. robusta. 

 Involucral teeth straight, not uncinate or recurved. 



Calyx 5-6 mm. long; plants erect. 21. C. valida. 



Calyx 4 mm. long; plants spreading. 22. C. Howellii. 

 Membranous margins continuous through the sinuses. 



Margins partly cleft; calyx-lobes bifid. 19. C. stellulata. 

 Margins not at all cleft; calyx-lobes entire. 



Leaves alternate on first internode; margins of involucral teeth purple. 



23. C. Douglasii. 



Leaves absent on first internode; margins of involucral teeth light pink. 



24. C. membranacea. 



