NUTRITION OF PARASITES AND SAPROPHYTES I2/ 



animals or on their remains, that is, on organic matter. Such 

 plants are called saprophytes, a plant having the life relation of 

 nutrition to dead or decaying organisms. The largest number of 

 species of both bacteria and fungi are saprophytes, and many of 

 them do very important work in the economy of nature, reducing 

 the substance of dead plants to the condition of humus which 

 improves the mechanical condition of the soil, removes the bulky 

 parts of plants, and sets free many substances which can be used 

 again for food by the green plants. Examples of these fungi are 

 the mushrooms, toadstools, puff balls, bracket fungi, molds, etc. 



NUTRITION OF PARASITES. 



Although the larger number of parasites 

 are among the fungi and bacteria there 

 are many parasitic flowering plants. A few 

 of these are briefly described here. 



209. Nutrition of the dodder. The 

 dodder, or " love vine" (Cuscuta), is a 

 slender twining plant which is parasitic 

 on clover, or some other cultivated plants 

 and on a great many weeds. There are 

 several species. The plant has very in- 

 conspicuous flowers developed in crowded 

 clusters. The seeds are small. When 

 the seeds germinate on the ground a root 

 is formed which attaches the plant to the 

 soil. But when the slender vine twines 

 around the living stem of its host, at the 

 places of contact it develops wedge-shaped 

 outgrowths which pierce the stem of the 

 host and penetrate the nbro-vascular 

 bundles. These outgrowths are haustoria, 

 or suckers, because they attach the vine 

 to its host and serve as absorbent organs. 

 There are nbro-vascular bundles in the 

 haustoria which connect with those of the vine and also form an 



Fig. 96. 



Dodder, showing stems 

 twining around its host (Im- 

 patiens). 



