GENERAL DESCRIPTION 383 



plants. Even the sapropliytic forms causo some undesirable 

 destruction. They often start in the wounds of fruit trees, shade 

 trees, and forest trees, and the action of their mycelia hastens 

 decay and may lead to the destruction of the tree. 



In many forms the mycelium, after it is well established in the 

 region of food supply, produces on the surface of the substratum 

 some kind of a body in which the spores are borne. It will be 

 recalled that this is the habit of the Morel. This body, since it 

 bears the spore, is called a sporophore which really means a 

 "spore-bearing body." It is a term commonly applied to a 

 spore-bearing hyphae or to any portion or all of the plant body 

 which has to do with bearing spores. Thus the wrinkled top and 

 stalk bearing it constitutes the sporophore in the Morel. In the 

 Toadstools and Mushrooms, the sporophore is often umbrella- 

 shaped. In some forms which grow on the sides of trees and 

 stumps, the sporophore resembles a small shelf projecting from 

 the support, and in this case the sporophore is often hard. In 

 PufTballs the sporophore is more or less globular. Sporophores 

 are extremely variable in both shape and texture, and are the 

 structures by which those Fungi which have them are classified. 

 The sporophore is the part of the Fungus that attracts attention. 

 It is the portion that is eaten and called a Mushroom. The 

 portion of the mycelium which traverses the substratum is usually 

 hidden, and its presence is not known until the sporophore 

 appears. 



Many of the parasitic Basidiomycetes, Hke the Smuts and 

 Rusts, have no conspicuous sporophores, and the presence of the 

 mycelium is indicated only by the occurrence of unusual struc- 

 tures on the surface of the host plant. In case of Smut the pres- 

 ence of the disease is indicated by the appearance of Smut balls, 

 and in Rusts, by the red or black blisters occurring on the leaves 

 and stem of the host. 



Although the basidiospores are the characteristic spores of the 

 group, a number of other kinds of spores occur, which in some 

 cases are more important in reproduction than the basidiospores. 

 Sexual reproduction has been entirely lost by many of the group, 

 and in those where it is retained the fusion is between hyphae, 

 there being no sex organs formed. There are no oospores or 

 zygospores to be considered in this group. 



The Basidiomycetes, of which there are 14,000 or more species, 



