The Lower Plants 77 



pendent radiating plates upon the lower side of the 

 cap. The spores are borne upon swollen club-shaped 

 cells, or basidia, and each spore is attached to a 

 short, slender stalk from which it is readily detached. 



In the lower types of Basidiomycetes, such as the 

 wheat-rust, the spore fruits are much less definite 

 in form, and several different sorts of spores are 

 produced in the course of the plant's development. 



Nuclear fusions occur at certain times, and these 

 fusions, in some of the lower Basidiomycetes, per- 

 haps represent a very rudimentary type of fertiliza- 

 tion. The relation of the Basidiomycetes to the sac- 

 fungi is not at all clear, and it is not unlikely that the 

 two classes are not related at all. 



Nutrition of Fungi. The fungi, as we have seen, 

 differ very essentially in their nutrition from the 

 green plants, being unable, so far as we know, to 

 utilize inorganic matter, except in the case of nitro- 

 gen, for the manufacture of organic food. Much 

 remains to be learned, however, about the nutrition, 

 which is often extremely peculiar. Many fungi feed 

 upon dead substances and are therefore important 

 agents in organic decomposition. Others are para- 

 sites, and often show extraordinary specialization. 

 A very remarkable type of parasitism is that known 

 as " hetercecism," where the parasite lives on more 

 than one host. This is the case in many rusts, one 

 of the commonest cases in Eastern America being 

 that of the rust Gymnosporangium, which produces 

 the conspicuous galls known as " cedar apples " 



