COMPOSITE. (j3 



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

 large terminal areola bearing around tlie hase of the .?t^■le a fle.^liv annular dislv. Lower 

 part of the disk-tiower,- and their chaff beset with some viilous hairs, like the verv luui; and 

 soft ones which thickly clothe the akene?. 



-I— •(— Akenes flattened, obcompressed, wing-margined. 



79. DICORIA. Female fluwers one or two, whoUy destitute of coroUa : male flowers 6 to 12, 

 with mere rudiments of ovary and style. Involucre of 5 oval or obloiif; herbaceous bracts; 

 and within one or two larger and broad tliin-scarious bracts, subtending tlie fertile flowers; 

 or these wanting in male heads. Eeceptacle small, flat, with a few narrow and hvaliue 

 chaffy bracts among the flowers. Filaments almost free from the obconical corolla, mona- 

 delphous up to the lightly connected anthers ! the tube dihited and 5-toothed at summit. 

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

 angled dorsally, abruptly bordered by a thiu-scarious pectinate-dentate wing or edge. Pap- 

 pus rudimentary, of several small and setiform sqnamelliE. 



* # Heads unisexual, moncecious : the fertile with solitary or 2 to 4 completely or nearly 

 apetalous female tl.j^evs in a closed nutlet-like or bur-like involucre, only the style- 

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

 the heads iu a raceme or spike of centripetal evolution : akenes turgid-obovoid or ovoid, 

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

 Ambrosiece, DC. 



-I— Involucre of the sterile heads gamophyUous ; the receptacle low, and abortive style with 

 dilated apex radiately penicillate or fimbriate. 



80. HYMENOOLEA. Involucre of the male flowers saucer-shaped and 4-6-lobed, rarelv 

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

 filiform or none : filaments distinct : anther-tips blunt. Involucre to tlie soUtary fertile 

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

 silvery-scarious persistent transverse winss. 



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

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

 chaff among the outer fiowers. Anther-tips (at first infiexed, at length erect) setiferons- 

 acuminate. Involucre to the solitary fertOe flower nucumentaceous, apiculate or beaked at 

 the apex, and usually armed with 4 to S tubercles or short spines iu 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-fiowered, 1-4-oelled, a single pistil to each ceU, 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 thaa one series. Leaves mostly 

 alternate. 



■^r- H— Involucre of the sterile heads polyphyllous, and the receptacle cylindraceous. 



83. XANTHIUM. Involucre of the globular sterile heads one or two series of small nar- 

 row bracts receptacle distinctly paleaceous, a cuneate or liuear-spatulate chaffy bract partly 

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

 infiexed apical appendage mucronate : sterile style imappendaged. Fertile heads a closed 

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

 clothed with uncinate-tipped prickles ■ each flower a single pistil, maturing n thick ovoid 

 akene, the two permanently enclosed in the indurated prickly involucre. Leaves alternate. 



Subtribe IV. Zixnie.e. Ray-flowers ligulate and fertile ; the lijjule with very shoit 

 tube or none, persistent on the akene and beccmin,; papery in texture ! (but at length 

 falling or decaying away in Heliopsis Iceris) : disk-flowers hermaphrodite and in our 

 genera fertile, numerous, subtended or embraced l.\v chaffy bracts ; the corolla cylin- 

 draceous. Leaves opposite and heads sin^dy terminating the stem 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 campanulate or cylindraceotis ; its closely appressed-imbricated 

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



