4192 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
The genus Oyedaea is closely related to Zermenia, Dimerostemma, 
and Aspilia. From Zermenia it is readily if somewhat artificially 
distinguished by its neutral rays. From Dimerostemma it differs in 
its round-sided achenes (four-angled and four-winged only in 0. hum- 
boldtiana), in its lack of a secondary external foliaceous involucre, and 
inits pappus. The pappus of Dimerostemma is composed of two awns 
only, without intermediate corona, although the lateral angles of the 
achenes are sometimes produced into short teeth or rarely into awns 
nearly or quite as long as those of the main angles. In a single 
species of Dimerostemma (D. asperatum) the awns are connected at 
base by their lacerate decurrent bases, but there is no true corona, 
constricted at base, such as is found in Oyedaea. The genus Aspilia 
is distinguished from Oyedaea by the fact that its achenes are not 
winged, although in some species there is a corneous auriculiform 
appendage on each of the upper angles of the achene. Oyedaea 
angustifolia and O. bonplandiana, possessing these appendages but 
lacking the continuous wing of Oyedaea, are here placed in Aspilia. 
SYSTEMATIC TREATMENT. 
OYEDAEA DC. 
Oyedaea DC. Prodr. 5: 576. 1836. 
Shrubs or herbaceous perennials, with opposite, entire to serrulate leaves and 
medium-sized yellow heads; heads heterogamous, radiate, the ray flowers 1-seriate, 
ligulate, neutral, those of the disk numerous, tubular, fertile; involucre 2 to 5-seriate, 
graduated, subequal, or with the outer phyllaries longer, the phyllaries lanceolate to 
oval or oblong, indurate at base or essentially throughout, usually with herbaceous 
tips, or the outer sometimes foliaceous; receptacle flattish or slightly convex; pales 
firm, concave, persistent; rays oval to linear-oblong, neutral; disk corollas with 
slender tube, cylindric or cylindric-funnelform throat, and 5-toothed limb; anthers 
sagittate at base, with ovate terminal appendages; style branches slender, dorsally 
hispid or hispidulous above, with short, lanceolate, hispid or hispidulous sterile 
appendages; disk achenes somewhat thickened but distinctly compressed, oblong 
or rarely cuneate-obovate, 2-winged (in one species 4-angled and 4-winged), the 
wings narrow or sometimes rather broad, usually united above to the awns o 
corona; pappus of 2 slender persistent awns and a corona of about 6 to 12 narrow, 
fimbriate or lacerate, more or less united squamellae. 
Type species, as here selected, Oyedaea verbesinoides DC. 
KEY TO SPECIES. 
Phyllaries oval or oblong to lanceolate, with indurate base and herbaceous, loose orr 
reflexed tip. 
Plants frutescent. 
Phyllaries oval or broadly obovate, with indurate base and herbaceous, usually 
rounded apex, the innermost in fruit somewhat elongate and with membra- 
nous-chartaceous rounded apex..................- 1. O. buphthalmoides. 
Phyllaries ovate or oblong to lanceolate, rarely obovate-lanceolate, acute to 
acuminate or rarely obtuse, the inner not elongate and membranous-char- 
taceous at apex. 
a 
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