138 



THE DICTIONARY OF GARDENING, 



Finns continued. 



PIG. 164. TRAMETES PINI, showing, (p) Pileus and ) Openings of 

 Spore-bearing Tubes, b, b, Bark of Fir-tree. 



form of Red Rot. It is often the cause of injury to 

 forests on the Continent ; but it is too rare in Britain to 

 give occasion for alarm. 



FIG. 165. AGARICUS MELLEUS, showing, at the base. Mycelium of 

 the Form called Rhizomorpha frayilis-h, Annuius, or Ring; 

 g. Gills ; v, Pileus. 



Agaricus melleus (see Fig. 165) very much resembles 

 Polyporus annosus in its effects upon the trees which it 

 attacks; but it is far less particular as to its host, not 

 by any means confining itself to Conifers. It is one of 

 the Mushroom group of Hymenomycetes, with the spores 

 produced on gills on the lower surface of the pileus. 

 The latter part is convex above and varies from honey- 

 colour to brownish, with blackish scales upon it. The 

 pileus, or cap, varies from 2in. to 7in. in breadth. The 

 caps spring up in large clusters, near the roots of trees, 

 or on them, or low on the trunk (see Figs. 166 and 167). 

 On tracing the mycelium, it will be found growing between 

 the wood and the bark, in black, string-like or flattened 

 bands, called Rhizomorpha subcorticalis and R. fragilis, 

 which were formerly regarded as distinct and independent 



Finns continued. 



species (see Figs. 168 and 169). Other Agarics also are 

 parasites, but none are equally dangerous with A. melleus. 



Another Fungus injurious to Fir-trees is Peridermium 

 Pini, which occurs upon both branches and leaves. The 

 branches are generally destroyed by it, the leaves 

 do not show signs of serious injury. See Perider- 

 mit 



FIG. 166. MASS OP AGARICUS MELLEUS ON ROOT OP YOUNG PINE 

 a, a, a, Mycelium in form known as Rhizomorpha fragilis ; 

 b, Very young Spore-bearers produced on Rhizomorpha fragilis ; 

 d. Older Spore-bearers (Af/aricus melleus) produced by Myce- 

 lium of form known as Rhizomorpha subcorticalis. 



The needles on various Conifers, in many parts of 

 the country, are very frequently studded with one or 

 more rows of small black bodies, which, under closer 

 examination with a lens, are found to have a slit running 

 from end to end of the upper surface. These are the 

 perithecia of several species of Fungi grouped together 

 in a genus called Hysterium. That on the Scotch Fir 

 is H. pinastri. It is hurtful by causing the premature 

 fall of the needles, and a consequent loss of nourishment 



FIG. 167. AGARICUS MELLEUS. Group of young Spore-bearers (c) 

 produced on Rhizomorpha subcorticalis (a), which is also shown 

 spreading upwards at d; b, Sterile Mycelium in form called 

 Rhizomorpha fragilis. 



to the trees. In each perithecium are numerous re- 

 latively large cells (asci), inclosing eight long, slender, 

 colourless spores. The tissues of the needles are early 

 traversed by the mycelium of the Fungus ; and the 

 needles fall off usually at the end of their first year 

 of life, but the Fungus is matured only after the leaves 

 have been lying on the ground for some time. 



It* must be borne in mind that unhealthy external con- 

 ditions, such as sterile soil, bad drainage, or lack of free 



