COMPOSITE. 03 



(sometimes with a single diaphanous and minute squamella to represent pappus!), with 

 large terminal areola bearing around the base of the style a fleshj annular disk. Low, r 

 part of the disk-flowers and their chaff beset with some villoua hairs, lik,- the very long and 

 soft ones which thickly clothe the akeues. 



-H- -i Akeues .flattened, obcompressed, wing-margined. 



79. DICORIA. Female flowers one or two, wholly destitute of corolla ; male flowers 6 to 12 

 with mere rudiments of ovary and style. Involucre of 5 oval or oblong herbaceous bra 

 and within one or two larger and broad thin-scarious bracts, subtending the fertile Il.,wcra 

 or these wanting m male heads. Receptacle small, flat, with a few narrow and hvaline 

 chaffy bracts among the flowers. Filaments almost free from (he obcouical corolla, i.i..i,a- 

 delphoua up to the lightly connected anthers! the tube dilate-.! and .Vtoothed at sum. nit. 

 Akeues much surpassing the outer involucre, oblong, anteriorly flat, convex or somewhat 

 angled dorsally, abruptly bordered by a thin-scarums pectinate-dentate wing or edge. Tap- 

 pus rudimentary, of several small and setiform squamelhc. 



* * Heads unisexual, monoecious ; the fertile with solitary or 2 to 4 completely or nearly 

 apetalous female flowers in a closed nutlet-like or bur-like involucre, only the st \ le- 

 branches ever exserted ; the sterile of numerous male flowers in an open involucre, 

 the heads in a raceme or spike of centripetal evolution: akeues turgid-obovoid or M\..id, 

 wholly destitute of pappus : flowers greenish or yellowish : male corollas obconical. 

 Ambrosiece, DC. 



-i Involucre of the sterile heads gamophyllous ; the receptacle low, and abortive style with 

 dilated apex radiately penicillate or fimbriate. 



80. HYMENOCLEA. Involucre of the male flowers saucer-shaped and 4-0-1.. bed, rarely 

 more cleft : bracts of the receptacle subtending the outer flowers obovate or spatulate ; inner 

 filiform or none: filaments distinct: anther-tips blunt. Involucre to the solitary fertile 

 flower ovoid or fusiform, beaked at apex, the lower part furnished with 9 to 12 dilated and 

 silvery-scarious persistent transverse wings. 



81. AMBROSIA. Involucre of the male flowers from depressed-hemispherical to turl.iuato, 

 5-12-lobed or truncate, herbaceous. Receptacle flat or flattish, usually \\ilh some filiform 

 chaff among the outer flowers. Anther-tips (at first inflexed, at lengih erect) setiferous- 

 acuminate. Involucre to the solitary fertile flower uucumentaceous, apiculate or beaked at 

 the apex, and usually armed with 4 to 8 tubercles or short spines in a single series below 

 the beak. Sterile heads spicate or racemose above the fewer fertile ones. 



82. FRANSERIA. Heads of male flowers as Ambrosia, or sometimes intermixed with 

 the female. Fertile involucre 1-4-flowered, 1-4-celled, a single pistil lo each cell, 1-4- 

 rostrate, more or less bur-like, being armed over the surface with several or numerous prickles . 

 or spines (the spiny free tips of component bracts) in more than one series. Leaves mostly 

 alternate. 



-i -i Involucre of the sterile heads polyphyllous, and the receptacle cylindraceous. 



83. XANTHIUM. Involucre of the globular sterile heads oue or two scries of small nar- 

 row bracts : receptacle distinctly paleaceous, a cuneato or linear-spat ulate chal'h bract partly 

 enclosing each male flower: filaments monadelphous : anthers distinct but comment; the 

 inflexed apical appendage mucrouate : sterile style uunppendaged. 1-Vriile heads a do>ed 

 and ovoid bur-like 2-celled and 2-flowered involucre, 1-2-beaked at. the apex, the surface 

 clothed with uucinate-tipped prickles: each flower n single pistil, maturing a thick ovoid 

 akene, the two permanently enclosed in the indurated prickly involucre. Lea\cs alieruate. 



Subtribe IV. ZINNIE.-E. Ray-flowers ligulatc and fertile; the, ligule with very short 

 tube or none, persistent on the akene and becoming p.-ipery in texture ! (but at Im-lli 

 falling or decaying away in Heliopsis Icevis) : disk-flowers lirrniaplirodile- and in our 

 genera fertile, numerous, subtended or embraced by diuflY bracts; the corolla cylin- 

 draceous. Leaves opposite and heads singly terminating the stein or branches. 



* Leaves all or mostly entire: akenes of the disk compressed, all or some of them (either 

 of disk or ray) toothed or awned from the summit of the angles or edges. 



84. ZINNIA. Involucre campauulate or cylindraceous; its closely appressed-imbricated 

 bracts dry and firm, broad, with rounded summit often margined. Receptacle becoming 



