POLYPORACE^E. 



POLYSTICTUS HIRSUTUS, Fries. 



This fungus has been found on limes in Dominica : it is 

 not clear as to whether it is parasitic or not. 



Diagnosis. — Pileus suberose-coriaceous, convex-plane, 

 with rigid hairs, homogeneous in colour, but zoned with 

 concentric grooves, white ; spores round, white, becoming 

 slightly dark in colour. 



SACCARDO : Sylloge Fnngorum, Vol. VI, p. 257. 



FOMES SEMITOSTUS, Berk. 

 (Root Disease of Para Rubber.) 



The disease occurs in the Federated Malay States and in 

 Ceylon. 



The fungus attacks the tap root of the plant, which 

 becomes soft and finally rots. Deprived of its tap root the 

 plant eventually dies ; it may. however, continue to live for 

 a time by absorption of food through the side roots. 



The mycelium of the fungus occurs as a white covering 

 on the diseased root, or sometimes as a network of white 

 strands. The strands pass upwards and appear above 

 ground at the base of the tree ; when old they are of a 

 yellowish colour ; they spread through the soil from one 

 plant to another. 



The sporophore of the fungus appears as a semi-circular 

 disc at the base of the tree. 



Diagnosis. — Perennial, imbricated, woody ; pileus dimi- 

 diate, about 10 cm. long and 6 cm. broad, at first red-brown 

 with a yellow, swollen edge, then pale yellow-brown with 

 concentric, dark-brown lines, smooth, feebly sulcate, 

 slightly silky with adpressed fibrils ; pore surface orange, 

 red-brown when old; pores minute, 'o6-'i2 mm. diamr., 

 rather widely separated, stratose, 2"5"3"5 mm. long ; flesh 

 white, woody, with concentric lines of growth curving 

 from the hymenium to the surface sulcse. 



PETCH : " Root disease of Hevea brasiliensis " ; Circ. 

 and Agric. Joum., Royal Bot. Gdns., Ceylon, Vol. Ill, 

 No. 17, 1906. 



RIDLEY: Agric. Bull, of the Straits, Vol. Ill, p. 174. 



34 



