THE GASTROMYCETES 



269 



tightly around the fructifications. These movements of the seg- 

 ments in certain species when alternately wet and dry sometimes 



tear the earth stars loose from 

 the ground so that they may 

 roll about, thus assisting in 

 the distribution of the spores. 

 The puffballs and earth 

 stars are in the same order 

 (Lycoperdales). 



The nest fungi. These beauti- 

 ful little forms (order Nidula- 



riales) grow on the earth and 

 FIG. 240. An earth star (Geaster) decaying wood and when open 



resemble a nest filled with eggs (Fig. 241). The egg-like struc- 

 tures are portions of the interior of the fructification, and each 

 contains a chamber filled with spores. 



The carrion fungi. These very malodorous fungi (order 

 Phallales) grow in rich humus and mulchings. They are com- 

 plicated stalked types first formed within a large globular 

 structure which remains around the base of the stalk as a cup. 

 The top of the stalk bears a dark-colored, sticky mass of spores, 

 that has the odor of carrion 

 and attracts carrion flies, 

 which probably assist in the 

 distribution of the spores. 



278. Mycorrhiza. Mycor- 

 rhiza (meaning fungus-in- 

 fected roots) is a remarkable 

 association of the mycelium 

 of certain fungi with the 

 roots of many seed plants, 

 notably trees. The fungal filaments surround the roots with a 

 web (Fig. 242) and enter the outer regions of the root tissue, 

 probably living somewhat parasitically upon the plant as a 

 host. They are in close contact with the soil around the roots, 



FIG. 241. A nest fungus (Cyathus) 



The section at the right shows the egg-like 

 structures containing the spores 



