208 



BOTANY 



the mineral salts from the soil, for it then depends only upon an 

 intimate union with the decaying substances. 



Cuscuta europaea (Fig. 185) may be cited as an example of a parasitic Phanero- 

 gam, a plant belonging to the family of the Convolvulaeeac. Although, through 

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



Fig. 1S5. — Cuscuta europaea. On the right, germinating seedlings. In the middle, a plant of Cusa'tc 

 parasitic on a Willow twig ; b, reduced leaves ; El, flower-clusters. On the left, cross-section of 

 the host-plant W, showing haustoria H of the parasite Cus, penetrating the cortical parenchyma 

 and in intimate contact with the xylem v and the phloem c of the vascular bundles ; s, ruptured 

 cap of sheathing sclerenchyma. 



latiug plants, in reality the amount of chlorophyll present is small, while the leaves 

 are reduced to mere scales. And as the devices for a parasitic acquisition of nourish- 

 ment are so easily seen, much more so, for instance, than in parasites which attack 

 their host-plant underground, it will be at once evident that Cuscuta (Dodder) 

 affords an example of a wonderfully well-equipped parasite. 



The embryonic Cuscuta plantlet, coiled up in the seeds, pushes up from the 

 ground in the Spring, but even then it makes no use of its cotyledons as a source 



