vii.] FLOWERING PARASITES 61 



us with a transition through a leafless species 

 to the order Monotropacece, which some botanists 

 separate from Ericacece because of their totally 

 greenless condition. It includes four genera, 

 one of which, the plant called " Bird's - nest " 

 (Monotropa Hypopitys], is British. Again, the 

 order Scrophularinece, which contains numerous 

 non - parasitic genera, as the fox - glove, snap- 

 dragon, musk, etc., has a tribe containing 

 eighteen genera, six of which are British, and 

 all but one have green leaves. They are also 

 all parasitic on grass or other roots. From this 

 tribe one passes to the order (Orobanchacece) 

 or broom-rapes, which are entirely greenless. 



Flowering parasites attach themselves by 

 penetrating root-hairs to their " host - plants," 

 or by means of suckers called haustoria ; these 

 are disk-like elevations produced by the super- 

 ficial tissues, from the centre of which the 

 root-like process arises, which penetrates the 

 stem of the host, and then grafts itself upon the 

 living tissues beneath the surface of the latter. 



As examples of illustrations of methods of 

 parasitism, I will take a leafy parasite, the cow- 

 wheat (Melampyrum) (figs. 17, 18), and a leafless 

 one, the dodder (Cuscutd). The former possesses 

 green leaves, and is not always attached to host- 

 plants ; for many individuals fix themselves, often 

 indeed the greater number, on decomposing pieces 

 of wood or even simply to a packet of humus very 



