DIV. i MORPHOLOGY 189 



characteristic segmentation of cormophytic plants, but grow altogether 

 within their host plant, whence they send out at intervals their extra- 

 ordinary flowers. In the case of Pilostyles, a parasite which lives on 

 some shrubby Leguminosae, the whole vegetative body is broken up 

 into filaments of cells which penetrate the host plant like the mycelium 



FIG. 220. Branch of a leguminous plant from the surface of which the flowers of a parasitic 

 plant (Pilostyles Ulei, Solms) are protruding. (From GOEBEL'S Organography.) 



of a fungus. The flowers alone become visible and protrude from the 

 stems and leaf-stalks of the host plant (Fig. 220). The largest known 

 flower, which attains a diameter of 1 metre, is that of the Sumatran 

 parasitic plant Rafflesia Arnoldi ; it is seated immediately on the roots 

 of its host plant, which is a species of Cissus. 



Cuscuta europea, (Fig. 221), a plant belonging to the family of the Convolvu- 

 laceae, may be cited as an example of a parasitic Phanerogam. Although, owing to 

 the possession of chlorophyll, it seems to some extent to resemble normally'assimi- 



