FUNGI 



387 



noted in (Edogonium. It does not directly produce a plant 

 like its parent. It produces a number of thin-walled sacs 

 or asci, and in each ascus a num- 

 ber of spores are found. (See 

 Figure 186.) Thus, as a result of 

 the sex process, a considerable 

 number of individuals are produced. 

 It is by means of the ascocarps 

 that this fungus lives over winter. 



d. Wheat Rust. — That parasitic 

 fungus which causes wheat rust 

 produces four distinct kinds of 

 spores. In this it is not entirely 

 different from other fungi of the 

 same group, but it is the one 

 whose pecuHar hf e history was first 

 understood. Its name is Puccinia. 



Like the rust of oats, wheat 

 rust is first noticed as rust-colored 

 marks on the stems and leaves 

 of its host. The rust-colored areas 

 spread. If you walk through a 

 field of rusted oats or wheat, your clothes become covered 

 with a reddish-brown dust. Under a microscope this dust 

 is found to be nothing but spores. The rusty patches on 

 the plant are nothing but spores. The mycelium, which 

 burrows among the tissues of the leaf and stem, has sent 

 hundreds of sporophores to the surface, and these have 

 borne thousands of these rust-colored spores. This kind 

 of spore is called the summer spore. By means of its sum- 

 mer spores this parasite spreads rapidly in a field where it 

 has gained a start. (See Figure 18'/.) 



Fig. 184. — Sex reproduction in 

 the bread mold. Note that 

 the ends of two hyphae which 

 come together are cut ofiE from 

 the rest of the mycelium by 

 cross walls. The parts thus 

 cut off fuse, and a dark colored 

 oospore results. — After Hunter. 



