390 POI.YGOXACEAE 



leaves or foliaceoiis bracts, both iu Oxytlieea ami (_'horizauthe. This dift'erenee 

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

 the ease in Oxytheea perfoliata. (Greek chorizo, to divide, and anthos, flower, 

 on account of the parted calyx.) 



A. Bracts entire. 



Involucres urnsliapeil or the tube eyliudric and slightly contracted below the teeth; teeth 

 equal or the 3 alternate shorter, bordered by a searious 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. mcnibranacea. 



Membrane purple, 3 of the involucral teeth usually incon.spicuous or minute 



2. C. nortoni. 

 Involucral teeth bordered by a narrow membrane but distinct. 



Calyx-lobes bitid, erect; Sierra foothills 3. C. steUulata. 



Calyx-lobes not bifid; Coast Ranges 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 searious margined. 



Involucral tube cylindric, usuall}' (i-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. breiicornu. 

 Joints less fragile. 



Calyx-lobes not fringed. 



Calyx-lobes entire; plant reddish. 



Calyx-lubes equal ; rare 7. C. ireweri. 



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. 



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

 fornia. 



Plants low, spreading horizontally; flowers white 12. C. parryi. 



Plants procumbent ; flowers yellow 13. C. procumheiis. 



Involucral teeth very unequal. 

 Involucre 6-ribbed. 



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



14. C. uniaristata. 



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



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



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

 transversely corrugated; calyx tubular, shortly 6-cleft; 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, tlie alternate 3 very short and inconspicuous; cauline leaves in 



pairs IS. C. polygonoides. 



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

 Involucral tube cylindric, not ribl^ed 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. tvatsonii. 



B. Bracts 3-lobed. 



Involucre without spurs, sometimes the angles gibbous at base. 

 Involucres 4-augled, 4-toothed. 



Bracts minute ; involucral teeth equal 22. C. vortriedel. 



Bracts very conspicuous and foliaceous, orbicular-perfnliate; teeth unequal 



23. C. perfoliata. 

 Involucres cylindric, not 4-augled. 



Involucral tube smooth, its teeth 4, unequal ; bracts unilateral. 3dobed, foliaceous 

 and conspicuous 24. C. caJifornica. 



