250 POLYPOREAE OF SOUTH AFRICA. 



species with the pore layers in successive strata. Trametes include 

 annual and perennial forms. It is distinguished from Polyporus 

 and Fomes by its usually pinky context and by having the pores 

 not in a definite layer but sunk to different depths in the context 

 tissue. The genus Favolus includes laterally stalked forms with 

 large angular pores radially elongated. Laschia spp. are small, 

 gelatinous, sessile, or stipitate polypores. In Lenzites, as mentioned, 

 the pores are replaced by plates, but, through forms which first 

 show a poroid character, this grades into the more typical pore 

 fungi and they are classed here rather than with the Agarics or 

 "Gill-fungi." In Daedalia the hy menial surface is labyrinthiform 

 and forms connect this genus with Polyporus and Trametes on the 

 one side and with Lenzites on the other. 



We include the genus Polystictus in Polyporus. No distinct 

 line can be drawn between these genera and in working over a 

 restricted area it is considered best to fuse them. The names 

 Polyporus and Polystictus have been applied almost interchange- 

 ably to the thin leathery polypores which are often separated under 

 the latter name. 



Very little is known about the South African resupinate forms 

 included in the genus Poria, and this genus is for the present 

 omitted . 



Economic Importance of the Group. 



From the utility point of view the object in preserving and 

 demarcating large tracts of forest areas is for the wood or timber 

 such areas can be expected to produce. Anything, therefore, which 

 may tend to reduce the annual rate of wood production or destroy 

 the wood already formed should receive careful attention. 



The "pore-fungi" are amongst the most serious of the fungi 

 responsible for rots in trees and timber. Some, for example, 

 Fomes rimosus, attack onlv the heartwood and cause what is 

 popularly called "heart-rot." Others, such as Fame* applanatus, 

 Polyporus lucidus, attack the sap-wood causing "sap-rot." 

 According to the nature of the parasitism we can distinguish forms 

 which only live on living trees and whose growth ceare with the 

 death of the host, for example, Fames rimosus and those which 

 usually grow on dead logs and wood, but may at times become 

 parasitic, for example, Fames applanatus, Pah/poru* lucidus, Poly- 

 porus sulphureus, Trametes obstinatus, Polyporus sanguineus, 

 Polyporus versicolor, and others. Those responsible for the decay 

 of trees all gain entrance through wounds. 



It is hoped that this paper may assist foresters in identifying 

 the fungus forms they meet in their different areas, and may in a 

 small measure contribute towards a better knowledge and under- 

 standing of those responsible for the decay of our South African 

 timber trees. 



Key to the Genera. 



1. Sporophores entirely resupinate and never developing pileate 

 forms. Poria (vide general account). 



