FUNGI 379 



may be so closely interwoven as to form a sort of mat, or 

 even to form what seems to be solid tissue, as in toadstools. 

 You may have noticed an example of mycelium on the sur- 

 face of moldy bread. 



From a common toadstool we may learn the general habit 

 of growth of all true fungi. Toadstools often make us 

 wonder. We wonder what they grow from and how they 

 grow so quickly. They seem to appear suddenly in the 

 night. They are saprophytes. The part we call a toad- 

 stool is the reproductive part. The nutritive part is hidden 

 in the rich soil or in the decaying wood or in whatever it 

 is from which the toadstool arises. This nutritive part is 

 a mass of burrowing and absorbing hairs. These hairs are 

 called hyphcB. The mass of them we have already called 

 the mycelium. The behavior of hyphae suggests the be- 

 havior of root-hairs. Like root-hairs they are much con- 

 cerned with absorption, but. they absorb food itself as 

 well as substances used in the manufacture of food. The 

 foods they absorb come mainly from the decay of the dead 

 parts of plants. The fallen leaves and branches with which 

 the floor of a forest is littered decay and become a part of 

 the soil of the forest, the part you have learned to call 

 humus. It is rich in organic material, and this material is 

 food for fungi. The mycelia of toadstools are usually 

 abundant in humus. 



The thing we call a toadstool is only a temporary part of 

 the plant. The permanent part is the mycelium. The 

 toadstool is a spore-bearing organ. The spore-bearing or- 

 gans of fungi are called sporophores. The advantage of 

 having sporophores above the soil is that the thousands of 

 light spores they produce may thus be scattered by the wind. 

 Some spores of fungi are light enough to float in the air. 



