374 



Hoiv Living Things Affect One Another unit vii 



Fig. 324 A plajit parasite, dodder, on golden- 

 rod. Special roots enter the host. Hoiv can dod- 

 der live without making chlorophyll? (blak- 

 iston) 



There is another special relationship 

 between organisms. Some plants live on 

 dead organisms, getting their food from 

 the dead tissue cells. They are called sap- 

 7-ophytes (sap'-row-fites). Saprophytes 

 are always plants, usually fungi of some 

 sort, either bacteria, yeasts, molds, or 

 mushrooms. A few seed plants are sapro- 

 phytes. See Figure 325. These sapro- 

 phytes lack chlorophyll and, therefore, 

 are unable to manufacture food as green 

 plants do. Their method of nutrition is 

 called saprophytism (sap'-row-fight- 

 ism). 



A relationship of benefit to both or- 

 ganisms. Certain protozoa spend their 

 lives within the intestine of the termite; 



Fig. 325 The hidian pipe is a saprophytic seed 

 plant. It does not make chlorophyll. Most sap- 

 rophytes belong to the group called ftmgi. 



(HUGH spencer) 



they need the food and the conditions 

 supplied by the digestive tract of the 

 temiite. But they are not parasites. They 

 aid the termite by digesting the wood on 

 which it has fed. If the protozoa are re- 

 moved, the termite dies of starvation in 

 the midst of plenty. Certain species of 

 bacteria live within the intestine of the 

 horse, helping it by digesting part of the 

 food the horse eats. Such a relationship 

 of mutual helpfulness between the mem- 

 bers of two species is called symbiosis 

 (sim-bi-oh'sis). Two plants may live to- 

 gether, too, each aiding the other. A 

 lichen (Figure 326) is really two plants, 

 an alga and a fungus living in partner- 

 ship. The alga makes the food used by 

 both. The fungus helps hold the water 

 needed by the alga for photosynthesis 

 and by both organisms for growth. 



Symbiosis is less common than para- 

 sitism. Sometimes, however, it is difficult 



