734 JOUENAL OF THE ROYAL HORTICULTUEAL SOCIETY. 



destructive to fruit-trees in this country is P. hirs2itus, which grows out 

 from the trunk like an inverted bracket, measuring from five to eight 

 inches across. The upper sm-face is brownish and coarsely hairy, the 

 under surface dingy greenish yellow, full of very minute holes or pores 

 containing the spores. The entire substance is rather soft and spongy, 

 and contains a quantity of water, which frequently drips from the lower 

 surface. 



A second kind, Polyporus fomentarius, also occurs on fruit-trees, but 

 is most abundant on Beech trunks. It somewhat resembles a horse's 

 hoof in shape, upper surface smooth, dark brown, and hard ; under side 

 flattish, pale, and pierced with very minute holes containing the brown 

 spores, which are produced in enormous numbers, and fall on the trunk 



Fig. 308. — Polyporus fomentarius. 

 A fungus destructive to various timber and fruit trees. 



and surrounding bodies in a mass resembling snuff. These s]Dores are 

 scattered by wind, and in turn infect other trees. 



Several other kinds of Polyporus and allied forms attack living trees, 

 and all agree in being wound-parasites. 



All such fungi should be cut away and the wound protected by a 

 coating of gas-tar. It is all-important that the fungi removed should be 

 burned, and not left lying about to shed their spores, as it is only by 

 means of spores carried by wind or other agents that healthy trees can 

 be infected. 



One of our commonest toadstools — Armillaria mellea — is very de- 

 structive to trees, and illustrates a peculiar mode of attack, exercised also 

 by other destructive parasites. A. mellea grows in dense clusters at the 

 base of trunks ; the cap is 2-3 inches across, brownish yellow, with 



