CLIMBING PARASITES. GREEN-LEAVED PARASITES. TOOTHWORT. 



175 



and energetically absorb food-materials. They withdraw organic compounds from 

 the host and convey them by a short route to the strands developed meantime 

 in the axis of the Cuscuta-stem. When once a union of this kind between 

 the parasite and the host has been established, the portion of the Cuscuta 

 situated below the first haustorium gradually dies. The lowest extremity, i.e. the 

 clavate tip, has already perished, so that the Cuscuta-plant is now no longer 

 in any connection with the ground whereon it germinated, but only remains 

 rooted to its living host by means of the suckers. If it has had the good fortune 

 to cling to a host with green foliage, which generates an abundance of organic 

 compounds, such as the luxuriant juicy stems of the Hop, or the Nettle, with its 



Fig. 35.— Cuscuta Europcea parasitic on a Hop-stem. 

 1 Natural size. 2 Section; x40. 



plentiful dark green leaves, which are shunned and spared by grazing animals on 

 account of their unpalatable stinging hairs, the parasite continues to grow with 

 extraordinary rapidity, and puts forth a number of branches immediately above 

 the lowest group of haustoria. All these again feel around with their tips, develop 

 tendrils and suckers, sometimes intertwining and becoming entangled together, 

 cover an ever-increasing area of the host with their network, and in this condition 

 fully deserve the name of " Hell-bind ", sometimes popularly applied to this plant. 

 Little spheres of rose-coloured flowers are then formed on individual threads of 

 this tangle, and from them balls of small capsular fruits, which dehisce by means of 

 lids and have their seeds shaken out by the wind. 



The European species of Cuscuta are all annuals. Even when their haustoria 

 are attached to perennial plants, as, for instance, on young branches of woody 

 plants, they wither after the seeds have ripened, and nothing is to be seen of them 

 in the following spring except a few dried tendrils coiled round branches of ash 

 or willow. But under a tropical sun, perennial species flourish as well. The 

 suckers of Cuscuta verrucosa, for example, continue to exercise their function 



