COMPOSITAE (COMPOSITE FAMILY) 455 
shorter spines like the points of a crown; whence its names of 
Kinghead and Crownweed. These spines, or tubercles, give much 
trouble in cleaning it from other seeds, as they catch in the screens ; 
also they contain air spaces, which enable the fruits to float on water 
and in winter to be blown far over crusted snow. (Fig. 317.) 
Means of control 
When young and tender, Great Ragweed succumbs readily to the 
blighting touch of chemical sprays. But if allowed to approach 
maturity it pays to hand-pull the weed, for the stout, woody stalks 
so dull and break the blades of mowers and reapers, cause so much‘ 
waste of binding twine, and are so clogging to the feed-way of 
threshing machines, that the earlier handwork is really an economy. 
In cultivated crops the plant gives little trouble, being killed there 
while young. 
COMMON RAGWEED 
Ambrosia artemistifolia, L. 
Other English names: Roman Wormwood, Bitterweed, Wild Tansy, 
Hayweed, Hogweed, Carrotweed, Stammerwort. 
Native. Annual. Propagates by seed. 
Time of bloom: July to September. 
Seed-time: August to November. 
Range: United States and Canada from Nova Scotia to British 
Columbia, southward to Florida and Texas. 
Habitat: Dry soil; cultivated ground, meadows, waste places. 
One of the most common of weeds, intruding almost everywhere ; 
it is a pest in meadows and pastures, for, though cattle do not relish 
its bitter juices, they will sometimes eat it when better forage is 
scarce and, as a consequence, yield bitter milk with a bad odor. 
After the removal of a grain crop this plant nearly always springs 
up in the stubble. When in bloom its abundant pollen is said: to 
cause “hay fever,” and it is dreaded and avoided by persons sub- 
ject to the disease. 
Ragweed has rather deep, branching roots, from which the stem 
rises one to five feet, erect, finely hairy, and branching freely. 
Leaves alternate, two to four inches long; thin, deep green above, 
paler beneath, twice pinnatifid, giving the plant an open, feathery 
