254 



DISEASES OF CULTIVATED PLANTS 



RHIZINA (FRIES.) 



Ascophore entirely sessile, expanded from the first, fleshy, 

 under surface furnished with numerous tufts of hyphae ; asci 

 cylindrical, 8-spored, spores elongated, continuous, hyaline. 



Readily recognised by the dark-brown, crust-like ascophore, 

 furnished on the under surface with numerous rhizoids or 

 tufts of hyphae, by which it is fixed to the substratum. 



Rhizina inflata (Quel.) is a fairly common British fungus, 

 met with on burnt soil, peat, etc., and often occurs abundantly 

 on old heaps of sawdust. The ascophore is somewhat convex, 

 more or less circular, margin often lobed, smooth, dark brown, 



FIG. 74. i, Rhizina inflata, nat. size ; 2, sections of fungus 

 showing rhizoids, nat. size; 3, ascus containing eight 

 spores, also three paraphyses, highly mag. ; 4, two free 

 spores showing the thickened ends, highly mag. 



3-10 cm. across; asci cylindrical, spores fusiform, 32-36 X 

 9-10 /A; paraphyses numerous, tips brown. 



Professor Hartig has shown that this fungus is parasitic 

 on the roots of young trees, more especially conifers, as Abies 

 pectinata, Tsuga mertensiana^ Pseudotsuga douglasti, Picea 

 sikkaensis, Pinus strobus, and Larix europaea. It also attacks 

 the roots of Castanea vtsca. On removing a plant that has 



