824 | 
32. Ambrosia (Tourn. }L. Koaqweed 
Annual or perennial branching leary herbs with mostly alternate pinnatifid 
leaves. Heaus small, sreenish, monoecious, the staminate pendulous, borne in 
Slender racemes at the tips of the branches, subtended by ¢ broadly funnels — 3 
shaped involucre$subegual to the whitish f flowers, the pistillate heads 1-flowered, 
borne either in short clusters below the staninate racemes or solitary in the 
upper axils, the ee Tesever ety Teronttne sePee ope Ovonlie, narrowed 
to a beak, ph ttt rr prt 
swinescant tasth—at—the—sioniterr> Achenes obovo i 
> 
o Pistillate involucres naked 
D pistillate involucres bearing a series of 5-6 
4 minute spinescent teeth above the middle 9 Ae elation © 
_—— eZ 
ey osilostachya Woe > Yerennial herbs 40- 80 cm. tall or more, 
with horizontal rootstocis, the stems thinly clothed with appressed stiffish 
hairs; leaves once or twice innatifid, the ultimate segments 2-4 cm. broad, 
both surfaces ash -nisvrid; staminate neads crowded in slender racemes 5-10 cm. 
long Which are arranged in panicles, their involucres Se eh 65-5 mm. 
lon,, hispidulous; pistillate heads solitary in tae upper axils, obovoid and 
beaked, hispidulous but devoid of small teeth on the shoulder, the achenes 
> Me 2 ae — a 
Cmeed ile lone 
Occasional as a weed in waste rlaces at low elevations. 
t 
BS 
me Ae clatior L. ~\~VA weedy SHUa Is 0-00 Cine tall, the stems thinly 
clothed with appressed stiffish hairs; leaves varied, tne lowermost opposite 
ana petiole, whe upper subsessile, eee! once or twice pinnatifid, the 
divisions <-5 mi. wide, acute, ¢rayisn-hispic; —>- 
, fe) 
Staminate heads 15-20- , tae involucres .e5-5 m.. tall, 
hispiduious; pistillate neads ovovoid, beaked, bearin, 5-6 minute srinose 
teeth near the shoulder, tne achenes smooth, obovoid, 2.5 mm. lon: at maturity. 
2 3 > x e 
Occasional as a weed in waste places. 
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