336 COMPOSIT AMBRORTA,. 
GZARTNERIA 
branaceous dilated-obovate or truncate ones which are strongly concave 
at maturity and half embrace the obovate-pyriform and glabrate akenes.”” 
Idaho and eastward. | 
Subtribe a, Ambrosiex DC. Prodr. v, 622. Heads wnisexual, 
monecious; the fertile with solitary or 2-4 completely apetalous or 
nearly apetalous pistillate flowers in a closed nut-like or bur-like invo- 
lucre, only the style-branches ever exserted: the sterile of nwmerous 
staminate greenish or yellowish flowers with obconical corollas in an 
open involucre, the heads in a raceme or spike of centripetal evolu- 
tion. Achenes turgid-obovoid or ovoid. Pappus wholly wanting. 
* Involucral bracts of the staminate head united. Receptacle low. 
36 AMBROSIA Tourn. L. Gen. n. 1057. 
Coarse branching monececious or rarely dicecious herbs with 
mostly lobed or dissected opposite and alternate leaves and small 
heads of greenish flowers the staminate heads racemose or spicate 
without subtending bracts, the pistillate below, commonly in 
small clusters in the axils of leaves or bracts. Involucre of the 
pistillate heads globose-ovoid or top-shaped, closed, 1-flowered, 
usually armed with 4-8 tubercles or spines: corollanone. Stamens 
none: style-branches filiform: of the staminate heads mostly 
hemispheric or saucer-shaped, 5-12-lobed, open, many-flowered. 
Receptacle nearly flat, naked or with filiform chaff. Corolla 
funnelform, 5-toothed. Style undivided, penicillate at the apex. 
A. artemisiefolia L. Sp. 987. Pubescent, puberulent or hirsnte pan- 
iculately branched annval, 1-6 feet high: leaves thin, bipinnatifid or pin- 
nately parted with the divisions irregularly pinnatifid; or sometimes nearly 
entire, on the flowering branches often undivided; racemes of sterile heads 
very numerous, 1-6 inches long, the involucres hemispheric, crenate, the ~ 
receptacle chaffy: fertile heads obovoid or subglobose, mostly clustered, 
1-2 lines long, short-beaked, 4-6-spined near the summit, sparingly pubes- 
cent, Dry plains and fields, eastern Washington to Brit. Columbia and 
the eastern States. 
37 GATSRTNERIA Medicus Act. Pal. iii, 244. 
FRANSERIA Cav. 
Herbs or woody plants with chiefly alternate, lobed or divided 
leaves and small moncecious rayless heads of greenish flowers : the 
staminate numerous, in terminal spikes or racemes: the pistillate 
solitary or clustered in the axils of the upper leaves. Involucre 
of the pistillate heads ovoid or globose, closed, 1-4-celled, 1-4- 
beaked, armed with several rows of spines and forming a bur in 
fruit: corolla none or rudimentary ; style deeply bifid, its branch- 
es exserted ; stamens none; achenes obovoid, thick, solitary in the 
cells: pappus none. Staminate -heads sessile or short-peduncled, 
their involucres broadly hemispheric, open, 5-12-lobed ; recepta- 
cle chaffy: corolla regular, the tube short, the limb 5-lobed: style 
undivided : anthers scarcely coherent, mucronate tipped. 
G. acanthocarpa Brit. Mem. Torr. Club v, 332. Franseria Hookeriana 
