THALLOPHYTA. 



685 



is a further justification for the inclusion of all these families — at first sight so 

 difierent — in a single alliance. 



Uredinem. — These are the Rust-fungi, parasites for the most part on the foliage 

 of higher plants. They are outwardly manifest in the form of yellow or brown 



Fig. 390.— Basidiomycetes. 

 laavariaaurea. ^ Dmdalia quercma. sMarasmius tenerrimus. i Marasmius perforans. i Craterellus clavatus. ^ Amanita 

 phalloides. 7 A portiou of the basidial layer of the last-named Fungus showing the sterigmata and conidia. » Uydnum 

 imbricatum. 9 Polyporus pereiinis. ' x 250 ; the rest nat. size. 



spots and streaks, due to the spores, which are formed in masses on the surface. 

 The mycelium inhabits the intercellular system of the host-plant, and draws its 

 nourishment from the living cells. The spores are regarded as chlamydospores, that 

 is to say, localized, thick- walled segments of the hyphse having the properties of 

 reproductive cells. These spores are met with in three forms in the Uredineae. The 



