COMPOSITAE (COMPOSITE FAMILY) 455 



shorter spines like the points of a crown; whence its names of 

 Kinghead and Crown weed. 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 artemisiifolia, 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 



