294 PLANT-LIFE 



Total parasites derive all their food from the host- 

 plants upon which they batten. The Toothwort 

 (Lathrea squamaria, Plate LIIL), doubtless descended 

 from honest ancestors, has lost all nobility; it takes 

 all its food from the roots of trees, particularly 

 Hazels, Poplars, and Beeches. The Broomrapes (Oro- 

 banche) are also total parasites. There are nine British 

 species, which draw nourishment from roots of Clover, 

 Ivy, and other plants. The Dodders, of which Britain 

 has only two native species, Cuscuta Europcea and G. 

 epithymum, belong to the Convolvulus family. We may 

 conclude that they were originally honest twining plants, 

 which, however, departed from virtue by inserting 

 suckers into their living supports at points of contact, 

 and thus extracting nutrient material. They gradually 

 descended in the scale of honour by depending more and 

 more upon their hosts and doing less and less of honest 

 labour, until at length they became " hangers on " of 

 the most vicious type. The Dodder battens on several 

 plants, such as Hawthorn, Gorse, and Wood-sage. Once 

 established on a Clover crop, Cuscuta trifolii, a variety of 

 G. epithymum, can do great damage, as a single plant 

 has been known to devastate no less than thirty square 

 yards of Clover in the course of three months. A thread- 

 like embryo is coiled up in the seed. On emergence 

 therefrom, in germination, it holds on to the ground by 

 one end, and the rapidly growing filament above ground 

 attaches itself to a host-plant, coiling round it in the 

 manner of a tendril. Should it fail to come in contact 

 with a host it must perish, as it is so degraded that it 

 cannot manufacture food for itself. At points of contact 

 with the stem of the host the parasite inserts suckers, 



