390 POLYGONACEAE 



leaves or foliaceous bracts, both in Oxytheca and Chorizanthe. This difference 

 is the more striking when it is associated with form differences as is notably 

 the case in Oxytheca perfoliata. (Greek chorizo, to divide, and anthos, flower, 

 on account of the parted calyx.) 



A. Bracts entire. 



Involucres urnshaped or the tube cylindric and slightly contracted below the teeth; teeth 

 equal or the 3 alternate shorter, bordered by a scarious membrane; stamens 6 or 9, 

 inserted at base or lower part of calyx-tube. 

 Involucre ' bordered by a broad membrane, the teeth excurrent from it. 



Membrane white, the 6 involucral teeth equal 1. C. membranacea. 



Membrane purple, 3 of the involucral teeth usually inconspicuous or minute 



2. C. nortoni. 

 Involucral teeth bordered by a narrow membrane but distinct. 



Calyx-lobes bifid, erect; Sierra foothills 3. C. stellulata. 



Calyx-lobes not bifid; Coast Eanges along the coast. 



Mostly prostrate or diffuse; membrane of involucral lobes not continuous around 



sinuses 4. C. pungens. 



Erect; membrane of involucral lobes continuous around sinuses.. 5. C. douglasii. 

 Involucres not scarious margined. 



Involucral tube eylindrie, usually 6-ribbed; stamens 6 or 9, inserted at base or lower part 



of calyx-tube. 

 Plants erect. 



Joints excessively fragile; calyx-lobes equal; plant yellowish .. 6. C. brevicornu. 

 Joints less fragile. 



Calyx-lobes not fringed. 



Calyx-lobes entire; plant reddish. 



Calyx-lobes equal ; rare 7. C. breweri. 



Calyx-lobes unequal ; common 8. C. staticoides. 



Calyx-lobes erosulate, very unequal 9. C. valida. 



Calyx-lobes, at least the inner, fringed. 



Lobes very unequal, the inner fringed 10. C, palmeri. 



Lobes equal, all fringed 11. C. fimbriata. 



Plants prostrate or procumbently spreading. 



Involueral teeth subequal or 3 long and 3 short; coastal area, Southern Cali- 

 fornia. 



Plants low, spreading horizontally; flowers white 12. C. parry i. 



Plants procumbent; flowers yellow 13. C. procumbens. 



Involucral teeth very unequal. 

 Involucre 6-ribbed. 



One tooth very long and 5 very short ; stamens 6 or 9 



14. C. uniaristata. 



Teeth very unequal ; stamens 3 15. C. clevelandii. 



Involucre 4 or 5-ribbed ; stamens 9 16. C. spinosa. 



Involucral tube 3 -angled, or cylindric but not ribbed or angled, in either ease usually 

 transversely corrugated ; calyx tubular, shortly 6-clef t ; stamens 6 or 9, inserted on 

 its throat. 



Involucral tube 3-angled; teeth stout, divergent. 

 Teeth equal or in equal sets. 



Teeth 3 ; cauline leaves usually none 17. C. orcuttiana. 



Teeth 6, the alternate 3 very short and inconspicuous; cauline leaves in 



pairs .- 18. C. polygonoides. 



Teeth 3, very unequal, foliaceous, ovate to lanceolate; very spiny.. 19. C. rigida. 

 Involucral tube cylindric, not ribbed or angled. 



Involucral lobes 3, equal, the tube strongly corrugated 20. C. corrugata. 



Involucral teeth or lobes 5, one foliaceous and much larger than the other 4, the 

 tube obscurely corrugated 21. C. watsonii. 



B. Bracts 3-lobed. 

 Involucre without spurs, sometimes the angles gibbous at base. 



Involucres 4-angled, 4-toothed. 



Bracts minute; involueral teeth equal 22. C. vortriedet. 



Bracts very conspicuous and foliaceous, orbicular-perf oliate ; teeth unequal 



23. C. perfoliata. 

 Involucres cylindric, not 4-angled. 



Involucral tube smooth, its teeth 4, unequal; bracts unilateral, 3-lobed, foliaceoua 

 and conspicuous 24. C. californica. 



