AMBROSIACEAE 1299 
achenes narrowly obovoid, oe 1 mm. DE muriculate.—Low pinelands and 
prairies, Coastal Plain, Fla. o S. C.—Sum.—winter.—Sometimes a weed. 
6. I. asperifolia Less. Annual, or perhaps sometimes perennial, 0.5 m. tall or 
less: stem sometimes de cumbent, UR e ir rs cent at least above: 
leaves narrowly elliptie to linear long, entire, aped 
punetate: heads con dp or approximate: E nm ubere about mm. 
high; bracts cuneate to suborbieular: achenes obovoid, about mm. es 
granular- botte do -plaees, Pensacola, Fla. Nat. of Mex. —Sum.—fall. 
2. AMBROSIA L. Annual or onal perennial coarse caulescent branch- 
. Leaves nei or opposite: blades as, lobed, or dissected, 
TN SRL Heads in spikes or racemes, the staminate above the pistillate, 
with a usually ced 5—12-lobed Pii PULS involucre erect, 
nut-like, usually with a single series of tubercles or spines near the apex, the 
beak truncate or 3- to 4-toothed.—About 20 species, mostly Ameriean.—RaAc 
WEEDS. | 
Staminate heads spicate: involucre very oblique, produced on the side away from 
he stem into a lanceolate acuminate lobe: annuals. I. CERCOMERIS. 
Staminate heads racemose: involucre slightly, if at all, oblique, 
not produced into an elongate lobe on either side: annuals or l 
perennials. II. EUAMBROSIA. 
I. CER 
A rough hirsute herb: leaf-blades of a lanceolate type, usually 
with a lobe on each side near the bas 1. A. bidentata. 
II. EUAMBROSIA 
ur: pma e pinnar id. 
Leaf-blades gre t above: plants annu 
Fruit-body 2-5 $ ines Mone the beak 1 n "dons or less. 
monophylla. 
Fruits rugose. 2. A: 
Fruits smooth. 3. A. glandulosa. 
Fruit-body mm. long or more, the beak more than 1 
mm. long. 
xU ‘of the lower is mostly posl IUE 
nts narrow: staminate heads abou 
4. A. elatior. 
Blades ‘of the lower leaves mostly rege the seg- 
s broad: staminate heads 4-5 mm. wide. 9. A. Rugeli. 
Leaf- ies pouce plants nm al. G. A. hispida. 
Leaf-blades entire, toothed, or 3-5-1 
um es uu d petioles : fruits. slightly if at all pitted 
tween t 
e ridges whieh end in short conic spines. 7. A. trifida. 
Leaves with wingless petioles: fruits poo between the 
ridges which end in tubercle- like spines 8. A. aptera. 
1. A. bidentata Michx. Stem tall or less, rough hirsute: leaf-blades 
lanceolate, linear-lanceolate, or ate ac. 2-8 em. long, each with a 
n lobe- ed tooth on one or both sides 
near the staminate involuere ue 
up pistillate heads solitary or tw 
gether in the axils: fruit 6-7 mm. jus Ea 
m 
adj. provinces, Miss. to Tex., Nebr 
Ky.—Sum.—fall. 
2. A. monophylla (Walt.) Rydb. Stem 
1.5 m. tall or less, pubescent with lax more 
or less scattered a Sn blades pclae 
bipinnati fid, or those of upper leaves 
innatifid or merely iota BER dE above, 
