Plants as Affected by Fungous Parasites. 171 



a By Flowering or phanerogamic (phan'-er-o-ga'- 

 mic) parasites. 



Of these, the only ones sufficiently common or injurious 

 to need mention are the broom rapes and the dodders. 



319. The Broom Rape of Hemp and Tobacco,* is the 



most injurious species of this class. The seeds germinate 

 in the soil, and the young plants attach themselves to the 

 roots of their host which they enfeeble by robbing them 

 of nourishment. In the case of hemp, the parasite also 

 injures the quality of the fibre. 



Preventives. The seeds of hemp or tobacco should not 

 be taken from a crop infested with broom rape. Infested 

 fields should be planted for se\'eral years to some crop 

 not attacked by broom rape, as potatoes, Indian corn, 

 beans, grains or grasses. In infested crops, the broom 

 rape should not be permitted to mature its seeds. 



320. The Dodders of Clover and Flax,f are the most 

 injurious of their class. The young plant attaches itself 

 to the stem of its host, about-which it twines, robbing it of 

 nourishment by means of small suckers. 



Preventives. The seeds of dodder are somewhat smaller 

 than those of clover or flax, and hence may be separated 

 from the latter by sifting. Badly iafested ground should 

 be devoted for two to four years to a crop not attacked 

 by the dodder. 



b — Plants as affected by fungous parasites. 



321. The Fungi constitute an extensive class of plants 

 that derive their nourishment wholly from organic matter. 

 Many of them are injurious to cultivated plants. Unlike 

 the harmful insects, most of which work their ravages 



* Philipiea ramona. t Cuscuta trifolia, C. Epillnum. 



