36 
DESCRIPTION OF MEDICINAL PLANTS. 
heads in dense eorymbed clusters ; leaves linear-lanceolate, 
partly clasping, decurrent ; scales yellowish-white, oval, 
acutish. Frequent in the uplands, in sandy soil. July- 
September. The herb, collected in flower. 
Parthenium integrifolium,, L. American Feverfew. A rough- 
pubescent perennial with an upright stiff* stem, terminating 
in a dense, flat corymb; leaves alternate, oblong or ovate, 
crenate-toothed, or the lower 3-6' long, cut-lobed below the 
middle ; heads many, in a very dense flat corymb. Flowers 
inconspicuously radiate ; ray-flowers 5, with very short and 
broad obcordate ligules not projecting beyond the woolly 
disk, pistillate and fertile; disk-flowers staminate with im- 
perfect styles, sterile. Involucre hemispherical, of two 
ranks of short ovate or roundish scales. Receptacle conical. 
Achenes only in the ray, obcom pressed, surrounded by a 
slender callous margin, crowned with the persistent ray- 
corolla and a pappus of two small chaffy scales. A substi- 
tute for the European Chrysanthemum Parthenium or Fever- 
fuge, which in the variety with double flowers is a favorite 
garden ornament. Our species is very frequent in the ar- 
gillaceous soils of the oak barrens. June -August. The 
whole plant in flower. 
Ambrosia artemisiaefolia, L. Ragweed. Covers all fields after 
wheat harvest. A coarse homely annual weed, much branched, 
1-3° high, hairy or roughish pubescent ; leaves thin, twice pin- 
natifid, smoothish above, paler or hoary beneath ; sterile 
flowers in single or panicled racemes or spikes; sterile invo- 
lucre top-shaped of 7-12 scales united. Fertile, involucre 
(fruit) oblong or top-shaped, closed, pointed, resembling an 
achene, obovoid or globular, armed with about 6 short acute 
teeth or spines. A fluid extract is prepared from the leaves. 
Xanthium spinosum, L. Cocklebur. A coarse and vile weed, 
perhaps the most unpleasant to deal with. It is an annual, the 
low and branching stout stems beset with slender, yellow, 3- 
parted, stout spines at the axils ; leaves lanceolate or ovate- 
lanceolate, tapering to a short petiole, white-downy beneath, 
