COMPOSITES. (COMPOSITE FAMILY.) 
221 
upper reduced to linear bracts, in the axils of which the heads are 
disposed, forming leafy panicled racemes; fertile flowers and scales 
of the involucre 5. — Sea-coast, Massachusetts to N. Jersey and south¬ 
ward. Aug. — A coarse plant, 3? - 8P high. 
28. AMBROSIA, Tourn. Rag-weed. 
Sterile and fertile flowers occupying different heads on the same 
plant; the fertile 1 - 3 together and sessile in the axil of leaves or 
bracts at the base of the racemes or spikes of sterile heads. Ster¬ 
ile involucres flattish or top-shaped, composed of 7 -12 scales unit¬ 
ed into a cup, containing 5-20 funnel-form staminate flowers. 
Fertile involucre oblong or top-shaped, closed, pointed, and usu¬ 
ally with 4-8 tubercles or horns near the top in one row, inclos¬ 
ing a single flower which is composed of a pistil only ; branches 
of the style elongated. Achenia ovoid : pappus none. — Chiefly 
annual coarse weeds, with opposite or alternate lobed or dissected 
leaves, and inconspicuous greenish or whitish flowers. ( Ap^po- 
aia, the food of the gods , an ill-chosen name for these worthless 
and coarse weeds.) 
1 trifida, L. (Great Rag-weed.) Stem tail and stout, 
square, rough-hairy, as well as the large opposite deeply Z-lobed leaves; 
racemes panicled; fruit (fertile involucre) 6-ribbed, the ribs terminat- 
i„* i„ as many crested tubercles. - Var. ,ntegr.f6lia has all the 
leaves, or the upper ones, undivided, ovate or oval, pointed. Low 
moist banks of streams, common, especially westward. — A coarse 
unsightly plant, 4° -12“ high. Leaves 4' -V broad, the lobes oval- 
lanceolate, serrate. 
2 A. artemisisefolia, L. (Roman Wormwood.) Stem 
slender, much branched (1° - 3= high), hairy or rough.sh-pubes- 
cent; leaves opposite and the upper alternate, twice-p.nnatifid, 
smoothish above, paler or hoary beneath ; racemes or spikes loosely 
panicled ; fruit obovoid or globular, pointed, armed with about 6 short 
acute teeth or spines.-Waste places everywhere. July-Sept.- 
An extremely variable weed, with finely cut leaves, embracing sev- 
eral nominal species. 
20. XANTHIUM, Toum. Cockle-burr. Clot-burr. 
Sterile and fertile flowers occupying different heads on the same 
plant; the latter clustered below, the former in short spikes or ra¬ 
cemes above. Sterile involucres and flowers as in Ambrosia, but 
the scales separate. Fertile involucre closed, coriaceous, ovoid or 
19* 
