18 



POLYGONACE^E. 



Eriogonum. 



Segments of perianth very unequal, the outer broad and subcordate : 

 cespitose perennials : inflorescence capitate or cymose-um- 

 bellate. 

 Densely cespitose : leaves round or oblong : head solitary, rarely 



cymose. 28. E. OVALIFOLITJM. 



Caudex more diffuse : leaves oblanceolate, acute : umbel 3-rayed, 



sparingly divided. 29. E. DICHOTOMUM. 



Segments similar, nearly equal, narrow at base. 



Perennials with short-branched caudex and naked peduncles : 

 bracts small : heads or fascicles solitary, or few in a long- 

 jointed cymose panicle (involucres sometimes solitary). 

 Dwarf, densely cespitose : head solitary : leaves small, linear- 

 oblong. 30. E. KENNEDY:. 

 Peduncles mostly tall and stout : caudex less branched. 



Heads large and dense, 1 or few : peduncle very stout, not 



fistulous ; tomentose. 31. E. LATIFOLIUM. 



Heads smaller, more numerous : leaves at least tomentose : 



peduncles more slender, fistulous. 32. E. NUDUM. 



Leaves large, villous : peduncles tall, fistulous, smooth. 33. E. ELATUM. 



Woody branched perennials : stems very leafy : leaves fascicled 

 and bracts mostly foliaceous : heads more or less closely 

 cymose-umbellate. 

 Flowers villous : leaves round to oblong, obtuse : bracts short : 



heads few and open. 34. E. CINERETJM. 



Flowers glabrous : leaves ovate to oblong, acute : bracts con- 

 spicuous : heads few, close. 35. E. PARVIFOLIUM. 

 Leaves narrowly oblanceolate, acute : umbel short and cymose, 



often much contracted or capitate. 36. E. FASCICULATUM. 



Involucres solitary (terminal and alar) in a repeatedly divided 

 corymb-like cyme : bracts mostly small : leaves not fascicled. 

 Perennial and woody. 



Low and diffuse, slender : leaves oblanceolate to linear : um- 

 bel short. 37. E. MICROTHECUM. 

 Stouter, more rigid, densely tomentose : leaves larger and 



broader : umbel broadly cymose. 38. E. CORYMBOSUM. 



Annual : leaves mostly rosulate at base. 



Floccose-woolly throughout : leaves oblanceolate : involucres 



2 lines long. 39. E. TRUNCATUM. 



Glabrous above : leaves rounded, small : involucres a line 



long : flowers minute. 40. E. MOHAVENSE. 



Hirsute : leaves rounded : involucres glandular. 41. E. LEMMONI. 



Involucres solitary along the often virgate branches of a naked 



dichotomous panicle : bracts mostly small. 

 White-tomentose perennials : panicle sparingly branched, usually 



virgate : involucre tomentose, teeth not margined. 

 Much branched at base : leaves oblanceolate, acute, often fas- 

 cicled : bracts small, triangular. 42. E. WRIGHTII. 

 Sparingly branched at base : leaves rounded : bracts larger, 



subfoliaceous : branches short. 43. E. SAXATILE. 



Sparingly branched : leaves lanceolate to ovate : involucres 

 larger (3 lines long), distant on the few elongated 

 branches. 44. E. ELONGATUM. 



Woody perennials : panicle diffuse with short rigid branchlets : 



involucres short, teeth more or less margined. 

 Glabrate above, divaricately branched, the branchlets sub- 



spinescent : involucres few, distant, campanulate. 45. E. HEERMANNI. 



Tomentose, taller : branchlets very short-jointed : involucres 



narrowly turbinate. 46. E. PALMERI. 



Annuals : leaves rosulate at base. 

 Tomentose throughout : branches virgate, few : involucres 



narrow, 2 lines long. 



Leaves oblanceolate : branches elongated : flowers glabrous. 47. E. VIRGATUM. 

 Leaves rounded : more diffuse : flowers villous. 48. E. DASYANTHEMUM. 



More slender and diffuse : involucres smaller. 



Leaves rounded : rather diffuse, often glabrous : involucres 



narrow, 1 lines long. 49. E. VIMINEUM. 



