196 SOUTH AFRICAN FLOWERING PLANTS. 



parasite, with a large white or rosy, ringent corolla, as 

 seen in Fig. 80. 



There are twelve South African species. The genus 

 is named after Dr. Harvey, the great South African 

 botanist, who commenced the Flora Gaioensis, now 

 being completed at Kew. 



When the root comes in contact with that of the 



yf^^' 



Fig. 



■ITarvey'a. 



host-plant, it swells by the growth of tissue beneath 

 the epidermis, or skin, while this last also begins to 

 grow at the spot, forming a sort of sucker. It then 

 sends out a kind of root, which penetrates down into 

 the root of the host, and becomes thoroughly engrafted 

 upon it. 



It is thus able to extract nourishment, and may in 

 time kill its host. The process of parasitism has a 

 degenerating effect upon the parasite, for, not requiring 



