244 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



50. Branches of the inflorescence terete, not sulcate, decidedly scabrous- 



papillate 48. E. HOWELLII. 



49. Branches of the inflorescence not rigid or divaricate or spinescent, or if 

 so, then more or less villous or lanate and the involucres also 

 lanate (51). 



51. Inflorescence not conspicuously cymose; involucres racemosely dis- 



posed and often crowded on the ultimate divisions of the inflo- 

 rescence, lanate; stems lanate; leaf blades linear-lanceolate, 

 elliptic, or oblanceolate, not more than 6 mm. wide; perianth 

 white or pink (52) . 

 52. Involucres divergent (not appressed to the branchlets), the teeth 

 obtuse or acutish, narrowly scarious-margined; stems woody 

 only toward the base, much-branched, dichotomously or tri- 

 chotomously so at the lower nodes, the ultimate divisions of the 

 inflorescence short and usually conspicuously secund. 



49. E. LEPTOCLADON. 



52. Involucres appressed to the branchlets, the teeth acute, not 

 noticeably scarious-margined; ultimate divisions of the inflo- 

 rescence not conspicuously secund (53). 

 53. Plant shrubby, intricately many-branched; involucres 1 to 1.5 

 mm. long, scattered along the branches; perianth 1.5 mm. 

 long, the outer lobes oblanceolate or narrowly obovate. 



50. E. PRINGLEI. 



53. Plant suffrutescent, few-branched; involucres 2 to 3 mm. long; 



perianth 2.5 to 3.5 mm. long, the outer lobes broadly obovate. 



43. E. WRIGHTII. 

 51. Inflorescence conspicuously cymose (54). 



54. Stems woody only near the base, lanate, at least below the in- 

 florescence (55). 

 55. Plant subscapose, with well-developed leaves only near the 

 base, these persistent; ultimate branches of the inflorescence 

 not flexuous, ascending; involucres lanate, their teeth acute, 

 not noticeably scarious-margined, often dark-colored. 



45. E. jonesii. 



55. Plant not at all scapose, with well-developed leaves nearly to 



the inflorescence, these fugacious; ultimate branches of the 

 inflorescence flexuous, divergent or even decurved; in- 

 volucres glabrous or glabrate except on the margin, their 



teeth obtuse, scarious-margined 41. E. plumatella. 



54. Stems woody almost to the apex ; leaf blades densel v lanate beneath 

 (56). 



56. Leaf blades oblong-lanceolate to broadly ovate, seldom less than 



6 mm. wide, cuneate to subcordate at base, irregularly undu- 

 late or crispate, not or only slightly revolute; petioles usually 

 well developed, often half as long as the blade; involucres 

 more or less lanate (57) . 

 57. Branches of the inflorescence ascending, not rigid or spines- 

 cent; perianth white or pink 51. E. corymbosum. 



57. Branches of the inflorescence divaricate, rigid, sometimes al- 



most spinescent; perianth white, pink, or yellow; inflores- 

 cence sometimes slightly glutinous 52. E. AUREUM. 



56. Leaf blades linear or lanceolate, seldom more than 4 mm. wide, 

 acute at base, strongly revolute; petioles usually very short, 

 rarely one-third as long as the blade; perianth white or 

 pink (58). 



58. Inflorescence glabrous or obscurely puberulent, relatively 



dense, broomlike, with the very numerous branches erect 

 or ascending at a narrow angle; leaf blades 2 to 5 cm. long, 

 very strongly revolute, the glabrous upper surface often 

 completely hiding the white-lanate lower surface; invol- 

 ucres glabrous or obscurely eiliolate, cylindric-turbinate; 

 perianth 3 to 4 mm. long, the outer lobes oblanceolate. 



53. E. LEPTOPHYLLUM. 



