382 DISEASES OF CULTIVATED PLANTS 



Forming patches 3-6 in. long, effused or partly reflexed, 

 fragile, rugose, brownish-white, rather fleshy, watery-zoned ; 

 tubes about \ in. long, pores white, roundish, the dissepi- 

 ments or walls of the tubes becoming torn into teeth at the 

 margin. Tubes forming nearly the whole of the fungus. 



Polyporus giganteus (Fries.). This large fungus grows 

 abundantly around old stumps, and also around the base of 

 trees not yet dead, and in all probability is a parasite, 

 although definite information on this point is not forthcom- 

 ing. For some years a very beautiful, large beech-tree, 

 growing in Kew Gardens, showed signs of being in some 

 manner unhealthy. Suddenly one season, and for the first 

 time, the ground under the tree was thickly studded with 

 very large tufts of P. giganteus. The following season the 

 tree died. When it was cut down, a thick felt of white 

 mycelium was found between the bark and the wood of the 

 lower part of the trunk ; the wood was also permeated with 

 mycelium, which formed white radial lines following the 

 medullary rays. The main branches of the root were also 

 saturated with mycelium, and in many instances the connec- 

 tion between tufts of the fungus and the root could be 

 distinctly traced. 



Tufts 2-3 feet across, formed of numerous overlapping pilei 

 or flaps, which are broad, flaccid, and tough, distinctly fibrous 

 when torn, often lobed, dingy greyish-brown, rather rough, 

 all springing from a common, stem-like, tuberous base. Tubes 

 short, pores minute, whitish, becoming dark coloured when 

 bruised, a character that at once distinguishes this from 

 allied species. 



Polyporus sulphureus (Fries.). This fungus is a wound- 

 parasite on many different kinds of trees, as oak, alder, 

 willow, poplar, false acacia or Robinia, larch, and different 

 fruit-trees. I once saw a magnificent specimen growing on 

 the trunk of an old yew in Yorkshire. After the mycelium 

 has gained an entrance the heart-wood is first disintegrated ; 

 during decay the wood changes to a reddish-brown colour 

 and becomes much cracked, the cracks being filled with 

 sheets of mycelium ; the mycelium also fills up the vessels 

 of the wood. 



P. sulphureus is perhaps the most beautiful of our poly- 

 pores, both as regards form and colour, but the smell is 

 strong and decidedly unpleasant. 



Tufted or imbricated, forming masses 9 in. to 3 feet across, 



