THE FUNGI 181 



Biology. Most of the Hymenomycetinese are saprophytes upon 

 dead vegetable matter, but a few are parasites, like certain species 

 of Polyporus, whose large, bracket-shaped fruits are so conspicuous 

 upon the trunks of trees, into whose living tissues the Fungus 

 penetrates through wounds in the bark. 



Reproduction. No form of sexual organs have yet been certainly 

 demonstrated for any of the Hymenoinycetineae, and the large fruit- 

 ing-bodies arise as vegetative growths from the mycelium. In most 

 of them basidiospores only are known, but conidia borne upon branch- 

 ing hyphae have been found in some species e.g. Coprinus (Fig. 

 147, F). The basidia form a definite layer, or hymenium, which 

 may cover the whole surface of the fruiting-body, but is more com- 

 monly restricted to certain definite regions, such as the " gills " of 

 the Mushroom. 



The fruit is made up of more or less closely compacted hyphse, 

 which may be grown together, so as to resemble a true parenchyma. 

 In the persistent fruits, such as that of Polyporus, the walls of the 

 cells are hard and woody in texture, but they are more commonly 

 delicate, and the fruit may be very ephemeral. Cells containing 

 pigments, and extensive milk-tubes, occur in some species. 



The mycelium, in the larger forms, lives for many years, growing 

 constantly and producing successive crops of fruits, or occasionally 

 the fruits are themselves perennial. 



Classification. The classification of the Hymenomycetineae is based 

 upon the form of the fruiting-body and the arrangement of the 

 hymenium. In the simpler forms like Clavaria (Fig. 149, A), the 

 hymenium covers uniformly nearly the whole of the branching fruit- 

 ing-body. In Hydnum (Fig. 149, B) the form of the fruit varies, 

 but the hymenium is confined to the pointed spikes which grow 

 from certain portions of its surface. 



The best-developed members of the order belong to the families 

 Polyporaceae and Agaricaceae. The former include many conspicu- 

 ous forms, of which the genus Polyporus is the type. To these 

 belong the large, massive, shelf -shaped Fungi, which grow upon the 

 trunks of trees or dead stumps. Another common genus is Bole- 

 tus, which has an umbrella-shaped fruit, like a Mushroom, from 

 which it differs, however, in the arrangement of the hymenium. 

 Thisjn all the Polyporaceae lines the walls of tubular, or more open 

 cavities, which appear as small pores upon the under surface of the 

 fruit (Fig. 149, C). 



Agaricaceae 



The Agaricacese comprise all the common Fungi known popularly 

 as Mushrooms and Toadstools, and are characterized by the well- 

 known umbrella-shaped fruiting-body, bearing upon the lower face 

 of the cap the dependent lamellae or gills, upon whose surface the 

 hymenium is borne. 



