350 PROCEEDINGS OF THE AMERICAN ACADEMY. 



National Herbarium, and the Gray Herbariinn. I wish to thank 

 Mr. W. R. IVIaxon and Dr. C. F. JVIillspaugh for the loan of the mate- 

 rial of Encelia under their charge, Mr. M. E. Jones for the loan of 

 11 sheets of Enceliojysis and for assistance in other ways, M. Casimir 

 de Candolle for a photograph of the type of Simsia lagascaeformis 

 and critical notes, and Dr. Philip Dowell for aid in proof-reading. I 

 am greatly indebted to Miss Mary A. Day of the Gray Herbarium for 

 assistance in proof-reading and for constant help in bibliographical 

 matters, and above all to Dr. B. L. Robinson for his advice and 

 guidance throughout the whole course of my work. 



Key to Encelia and some related Genera. 



Achenes very flat; no squamellae except in H dianlhella and Enceliopsis. 



Achenes winged; rays usually fertile Verbesina L. 



Achenes wingless; rays neutral. 

 Squamellae present. 



Usually leafy-stemmed herbs of mountainous regions, with green 

 leaves and frequently foliaceous outer involucral bracts; 

 squamellae mostly narrow, laciniate, and united at base; 

 achenes not villous or white-margined. Helianthella T. & G. 

 Scapose desert plants with canescent or silvery broadly oval or 

 rhombic leaves; outer scales never foliaceous; squamellae 

 short and indistinct, mostly united into a low sometimes en- 

 tire crown; achene villous except in E. grandiftora, and strongly 



white-bordered Enceliopsis (Gray) A. Nels. (p. 351.) 



No squamellae. 



Scapose, with broad leaves and large solitary heads. . (Enceliopsis) 

 Leafy-stemmed (except E. scaposa, which has linear leaves); heads 

 several (except in two .species with linear leaves), small or 

 medium-sized. 

 Pales soft, bluntish, falling with the achenes; leaves alternate; 

 achenes villous at least on margins. 

 Perennials; style-branches bluntish, not villous; achenes 

 without crown, usually epappose. 



Encelia Adans. (p. 358.) 



Annuals or biennials; style-branches longer, villous; achene 



narrowly cuneate, with strong white margin, awns, and 



crown Geraea T. & G. (p. 355.) 



Pales rigid, acute or acuminate, persistent; lower leaves oppo- 

 site; style-branches attenuate, hispid-villous; achenes not 



villous-ciliate Simsia Pers. (p. 376.) 



Achenes thickened; squamellae often present. 



Pappus caducous, of paleaceous awns and rarely short squamellae; herbs. 



Helianthus L. 

 Pappus more persistent 29 ; awns often aristate, squamellae usually present; 

 herbs or shrubs. 

 Squamellae none, or narrow and acute; achenes usually densely villous; 



alternate-leaved usually glutinous shrubs Flourensia DC. 



Squamellae present, mostly short, rounded, fimbriate; herbaceous or 

 frutescent, very rarely resiniferous, often opposite-leaved. 



ViGUIERA HBK. 



29 Caducous in some Viguieras, e. g. V. Mandoni Sch. Bip. 



