22 POLYGONACEAE 



Petioles of basal leaves slender, not winged. 46. E. gracile. 

 Petioles of basal leaves conspicuously winged by the decurrent blades, 

 the margin crenately crisped. 47. E. citharaeforme. 



Leaves rounded to broadly ovate. 



Stems simple below, glabrous; branches few, erect, forming a narrow crown. 



48. E. molestum. 



Stems branched from or near the ground, often tomentose, much branched 

 above into a broad crown. 49. E. vimineum. 



Inflorescence with short branchlets, usually composed of a single internode; involucres 

 borne in the axils and at the ends of the branchlets. 

 Branches of the inflorescence numerous forming a broad crown, the ultimate 

 branchlets filiform and pedicel-like; flowers yellow. 



SO. E. mohavense. 



Branches of the inflorescence few, forming a cyme-like inflorescence. 



Leaves oblong-obovate, narrowed to the petiole; stems and involucres tomen- 

 tose, the latter truncate as apex. 51. E. truncatum. 

 Leaves rounded, more or less cordate at base; stems and involucres glabrous, 

 the latter more or less turbinate. 



Involucres 5-veined, the S teeth short or obsolete. 



52. E. Covilleanum 



Involucres 8-veined and -toothed, broadly turbinate. 



53. E. Nortonii. 



Perennials, herbaceous or shrubby. 



Calyx villous-pubescent on the outer surface; shrubby; involucres subsessile or short-pedicelled, to- 

 mentose. 54. E. deserticola. 

 Calyx glabrous. 



Calyx tapering into a stipe-like base, becoming 5-7 mm. long in age. 



Involucres in a compact divaricately branched cyme, broadly campanulate; petiole broad and 

 winged. 55. E. crocatum. 



Involucres scattered along the virgate branches of the inflorescence; petioles slender, not winged. 



56. E. saxatile. 

 Calyx not elongated at base, 1-3 mm. long. 



Outer surface of involucre tomentose. 



Calyx-lobes dissimilar, the outer broadly elliptic, rounded at base. 



57. E. niveum. 

 Calyx-lobes similar, usually obovate. 



Inflorescence indefinite; flowers mostly racemosely disposed. 



Involucres on the main ascending branches, racemosely disposed or scattered. 

 Flowers racemosely disposed; involucres 2-3 mm. long. 



Plants cespitose with a much branched caudex; leaves oblanceolate. 



58. E. Wrightii. 



Plants scapose from a simple or few-branched caudex; leaves ovate to 

 oblong-ovate. 

 Flowers scattered ; involucres 5-7 mm. long. 

 Involucres on lateral divaricate branchlets. 

 Inflorescence a compact terminal corymbose cyme. 

 Outer surface of the involucre glabrous. 



Cespitose perennial with scapose flowering stems. 



Low desert half-shrubs with intricately branched stems, leafy below. 

 Outer calyx-lobes obovate, narrowed at base. 

 Outer calyx-lobes suborbicular, subcordate at base. 

 Involucres in heads of two or more, rarely solitary; perennials. 



Cespitose perennials, the caudex low, much branched, forming dense mats or cushions; flowering stems 

 scape-like. 

 Calyx-lobes dissimilar, the outer much broader and cordate at base. 



Inflorescence a single terminal head. 66. E. ovalifolium. 



Inflorescence cymose-umbellate. 67. E. proliferum. 



Calyx-lobes similar, not cordate at base; involucres in a single head terminating the scape-like flowering 

 stem. 

 Leaves oblanceolate or spatulate, long-petioled, not revolute. 68. E. ochrocephalum. 



Leaves oblong-linear, strongly revolute, subsessile or short-petioled. 69. E. Kennedyi. 



Shrubs, or if herbaceous the caudex not cespitose; calyx-lobes similar at least in age. 

 Perennials, with a more or less woody root crown or short few-branched caudex. 

 Leaves spreading, oblong-ovate, obtuse, 2-5 cm. long. 



Involucres and usually the flowering stems glabrous. 



Heads one or few; stems not fistulous. 70. E. latifolium. 



Heads usually several to many; stems fistulous. 



Leaves in basal rosettes crowning the rootstocks. 71. E. nudum. 



Leaves scattered along the branches of the erect woody caudex. 



72. E. grande. 

 Involucres and flowering stems tomentose. 73. E. Harfordii. 



Leaves erect, ovate-lanceolate, acute, 4-12 cm. long. 74. E. elatum. 



Shrubs 3-15 dm. high. 



Leaves orbicular to linear-oblong, not fascicled. 



Calyx glabrous without; heads mostly few and scattered. 75. E. parvifolium. 



Calyx villous without. 



Heads few, scattered along the stem. 76. E. cinereum. 



Heads many in compound cymes. 



Leaves ovate to oblong-ovate. 77. E. giganteum. 



Leaves linear-oblanceolate, revolute. 78. E. arboresccns. 



Leaves narrowly linear, fascicled; flowers umbellate. 79. E. fasciculatum. 



