264 



THE FUNGI 



and the different types of life histories affecting various hosts; 

 but many of the forms have no economic importance, being 

 found on such plants as the violet, May apple, cocklebur, 

 asters, golden-rods, members of the pea family, etc. However, 

 there are destructive rusts on the roses (Phragmidium), clovers 

 (Uromyces), blackberries (Oeoma), etc. An interesting type is 

 the rust (Gymnosporo iiijitiin) which causes the distortions called 

 cedar apples on the junipers, and the much-branched stunted 

 growths called witches' brooms. This rust has a cluster-cup 

 stage (once named Ewstelia) on the hawthorn and apple. 



SERIES II. THE TYPICAL BASIDIA FUNGI, on EUBASIDIOMYCETES 



276. The Hymenomycetes. This group, which may be con- 

 sidered a sub-class of the Basidiomycetes, comprises all of the 



higher basidia fungi whose spores are 

 developed on a fruiting surface, called 

 an hymenium (meaning a membrane), 

 which is exposed. This condition is 

 thus contrasted with that in the Gas- 

 tromycetes (puffballs, etc.), where the 

 spores are developed within a case. The 

 types of fructification are exceedingly 

 various in this group, which includes 

 the pore, the tooth, and the gill fungi 

 in the various forms of toadstools and 

 brackets. But there are also some 

 simpler types, as the coral fungus (Cla- 

 varia), with irregular branches (Fig. 

 234), and also some expanded forms. 

 The pore fungi. The pore fungi 

 (family Polyporacece) have commonly the shape of brackets and 

 grow on the trunks of trees, although some are large, fleshy toad- 

 stools, as Boletus (Fig. 235). The hymenium lines the cavities 

 of the numerous pores which are found on the under surfaces. 



FIG. 234. A coral fungus 

 (Clavaria) 



