BUCKWHEAT FAMILY 71 



Leaves scattered on the fruticose branches; blades tapering at the base. 



Leaf-blades elliptic or oblanceolate. 90. E. Wrightii. 



Leaf-blades linear. 91. E. leptocladon. 



XVI. VIRGATA. 



Stem neither divaricately branched, nor densely floccose. 



Involucres cyUndric; perianth-segments oblong or oval; plant with few branches. 

 Involucres about 3 mm. long. 92. E. vimineum. 



Involucres about 2 mm. long. 93. E. Baileyi. 



Involucres campanulate, 1-1.5 mm. long; perianth-segments cxmeate, flabellate, or 

 flddle-shaped ; plants with numerous branches. 

 Branches not incurved in age; leaf-blades ovate or oblong. 



94. E. densum. 

 Branches incurved in age; leaf-blades orbicular or subreniform. 



95. E. nidularium. 

 Stem divaricately branched, densely floccose. . 96. E. Plumatella. 



XVII. Pedunculata. 

 Perennials with a woody caudex. 97. E. tenellum. 



Annuals. 



Perianth glabroiLS or in E. Thomasii a,nd E. nutans somewhat pubescent; segments 

 mostly obtuse or rounded at the apex. 

 Peduncles not glandular. 



Scape and its branches glabrous. 



Pedimcled reflexed or at least divaricate; leaves tomentose on both sides, 

 less so above. 

 Involucres 1.5-2 mm. long; perianth 1.5-2 mm. long. 



Peduncles shorter than the involucres ; outer perianth-lobes ovate or 

 subreniform. 

 Perianth pale yellow; outer segments subreniform. 



98. E. Ilookeri. 

 Perianth wMte; outer segments ovate. 99. E. deflexum. 

 Peduncles longer than the involucres; outer perianth-segments 

 obovate or pandm-iform; perianth wliite or pinkish. 



100. E. cernuum. 

 Involucres 0.5 mm. long; perianth 1-1.5 mm. long, yellowish with red- 

 dish veins. 101. E. Wetherillii. 

 Peduncles erect or ascending. 



Leav^es more or less tomentose beneath. 

 Involucres 1.5-2 mm. long. 



Perianth yellow; segments similar. 102. E. pusillum. 



Perianth white or rose-colored; segments unlike. 



Involucres campanulate; outer perianth-segments flabellate. 



103. E. rotundifolium. 

 Involucres turbinate; outer perianth-segments not flabellate. 

 Outer perianth-segments oblong-ovate, the inner ones 



entire. 104. E. insigne. 



Outer perianth-segments subreniform, the inner ones 3- 

 toothed, much smaller. 105. E. turbinatum. 



Involucres scarcely 1 mm. long; perianth yellowish or white, usually 

 somewhat hispidulous at the base. 106. E. Thomasii. 



Leaves green, glabrate or sparingly pilose. 107. E. Gordonii. 

 Scape more or less pubescent, at least at the nodes. 



Leaves white-lanate beneath. 108. E. subreniforme. 



Leaves green on both sides, sparingly pilose. 109. E. trinervatum. 



Peduncles glandular; leaves tomentose. 



Outer perianth-segments oval, emarginate or retuse, the inner ones oblong. 



110. E. nutans. 



Outer perianth-segments ovate-cordate, the inner ones oblong-ovate, acute. 



111. E. Parryi. 

 Perianth pubescent; segments ovate or lanceolate, acute. 



Peduncles and usually also the scape glandular; leaves green, merely hirsute be- 

 neath. 112. E. glandulosum. 

 Peduncles and scape not glandular. 



Leaves floccose or tomentose beneath. 113. E. Ordii. 



Leaves green, merely pilose or hirsute. 



Accessory branches at the lower forks of the inflorescence many and nearly 

 as strong as the primary ones; all divaricate. 

 Scape slightly if at all inflated. 114. E. trichopodutn. 



Scape strongly inflated under the flrst node. 115. E. fusiforme. 

 Accessory branches of the lowest node of the inflorescence few and small 

 or none; branches ascending; scape usually inflated. 



116. E. inflatum. 

 XVIII. Divaricata. 

 Leaves green, puberulent; involucres 5-cleft. usually sessile. 117. E. divaricatum. 

 Leaves floccose beneath; involucres 5-toothed, peduncled. 118. E. angulosum. 



XIX. PUBERUL-V. 



One species. 119. E. puberulum. 



XX. Spergulina. 



Leaves green, merely pilose; scape glandular. 120. E. spergulinum. 



Leaves tomentose beneath; scape finely pubescent. 121. E. pharnaceoides. 



