PLATE 24. 



COMMON RAGWEED, Ambrosia artemisixfolia, L. 



Other English names : Eoman Wormwood, Smaller Ragweed, Hogweed. 



(Noxious: Dom.). 



Native. Annual. A coarse weedy branching plant, with hairy stems, 

 2 to 4 feet high. Leaves thin and much cut up, twice divided. Flowers and 

 fruit [Plate 55, fig. 58 natural size and enlarged 4 times] much resembling 

 those of the Great Ragweed but smaller. Occasionally plants may be found 

 which bear only fertile flowers. 



Time of Flowering : July ; seed ripe August. 



Propagation : By seeds, carried in the seeds of grain, clover and grasses. 



Occurrence : In rich land and waste places throughout Eastern Canada 

 and gradually extending into the Prairie Provinces. 



Injury : The seeds are an impurity in clover, small grains and grass seed. 

 The large spreading roots rob crops of moisture and plant food, and the free 

 branching growth chokes out weaker plants. 



Remedy : As the Ragweeds develop late in the season, roots and other 

 crops should be hand-hoed after the usual horse cultivation. Land badly in- 

 fested can be cleaned by a regular system of short rotations, care being taken 

 to cultivate immediately after harvest, and to mow down the fall growth on 

 new meadows. 



THE PERENNIAL RAGWEED, Ambrosia psilostachya, DC., is a western plant 

 found on the prairies, resembling the Common Ragweed in the shape of the 

 leaves and flowers, but with running perennial rootstocks which throw up 

 at intervals weak stems 1 to 2 feet high, covered with hoary-pubescent leaves. 

 This Ragweed is seldom troublesome in Canada either as a weed on farm 

 land or from the seeds occurring among crop seeds. With the more exten- 

 sive cultivation of grasses and alfalfa for seed in th" West it may be ex- 

 pected that this plant may require more attention. The seed [Plate 55, fig. 

 59 natural size and enlarged 4 times] resembles that of the above very 

 closely, but is, as a rule, more regularly oval and without the spines, al- 

 though seeds bearing spines are not uncommon. 



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