POLYGONACEAE. 103 



V. Lachnogyna. 



Leaves and scape silky ; the latter elongated, i dm. or more high ; the former 

 2-4 cm. long, long-petioled ; blades oblanceolate to oblong, acute. 



Inflorescence irregularly branched. 14. E. lachnogynum. 



Inflorescence subcapitate. 15. £. Tetraneiiris. 



Leaves lanate, strongly revolute ; scape usually none. 16. E. acaule. 



VI. Heterosepala. 



Involucres about 7 mm. long; leaf -blades oval. 17. E, orthocaulum. 



Involucres 4-5 mm. long. 



Perianth bright yellow, or purplish ; leaf-blades about as broad as long. 



18. E. ovalifolium. 

 Perianth cream-colored to isabel-colored ; leaf-blades elliptic to oval or spatu- 

 late, decidedly longer than broad. 19. E. ochroleucum. 



VII. Capitata. 

 Perianth yellow. 20. E. chrysocephalum 



Perianth white or brownish or pinkish. 



Perianth pubescent. 21. £. multiceps. 



Perianth glabrous. 



Lobes of the involucres much shorter than the tube. 



22. E. coloradense. 

 Lobes of the involucres about as long as the tube. 23. E. pauciHorum. 



VIII. Corymbosa. 

 Perianth yellow. 



Leaves crowded on the short branches of the caudex ; blades oblong to linear- 

 oblong, flat. 24. E. campanulatum. 

 Leaves more scattered on the elongated branches of the caudex ; blades nar- 

 rowly linear, strongly revolute. 25. E. brevicaule. 

 Perianth white or pinkish. 



Shrubs or herbaceous plants with a woody caudex, mostly over 2 dm. high ; 

 leaves not heath-like. 

 Flowering branches leafy only at the base. 



Involucres in the forks of the inflorescence sessile. 



Leaves mostly flat ; involucres narrowly turbinate ; perianth 2-2.5 mm. 

 long. 26. E. lonchophyllum. 



Leaves mostly revolute ; involucres campanulate ; perianth 3-3.5 mm. 

 long. 27. E. nudicaiile. 



Involucres in the forks of the inflorescence distinctly peduncled, at least 

 the lower. 

 Involucres broadly campanulate, about as wide as long. 



28. E. scoparium. 

 Involucres turbinate, decidedly longer than broad. 



Leaves narrowly linear-oblanceolate or linear, usually revolute. 



29. E. tristichum. 

 Leaves spatulate to oblanceolate, flat. 30. E. salicinum. 



Flowering branches leafy halfway or more. 



Leaf-blades relatively broad, broadly oblong to oval, obtuse. 



Involucres 4-5 mm. long. z^- E. F endlerianum. 



Involucres 2-2.5 mm. long. 



Branches of inflorescence divaricate. 32. E. divergens. 



Branches of inflorescence ascending. 33. E. corymbosum. 



Leaf-blades narrow, from spatulate to linear, acute. 

 Leaf-blades spatulate or oblanceolate, mostly flat. 



Inflorescence many times compound; copiously branched; internodes 

 long. 

 Inflorescence tomentulose, broom-like, with strongly ascending 

 branches; involucres about 1.5 mm. long. 34. E. effusum. 



