DIV. I 



THALLOPHYTA 



463 



FIG. 412. Clavaria botrytis. (Nat. size.) 



substratum. The mycelium of the forms vegetating in the soil spreads farther 

 and farther, and dying in the centre as it exhausts the food material of the 

 substratum, occupies continually-widening, concentric zones. In consequence of 

 this mode of growth, where the development has been undisturbed, the fructifica- 

 tions, which appear in autumn, form the so-called fairy rings. A few Hymeno- 

 mycetes are parasitic, and vegetate 

 in the bark or wood of trees. " n '-'"//' i 



The Hymenomycetes are 

 further classified according to the 

 increasing complexity exhibited 

 in the structure of their basidial 

 fructifications. 



1. In the group of the Thele- 

 phoreae, distinctive fructifica- 

 tions of a simple fype are found. 

 They form on the trunks of trees 

 either flat, leathery incrustations 

 bearing the hymenium on their 

 smooth upper surfaces ; or the 

 flat fructifications become raised 

 above the substratum and form 

 bracket -like projections, which 

 frequently show an imbricated 



arrangement, and bear the hymenium on the under side (e.g. Stereum Mrsutum, 

 common on the stems of deciduous trees). The edible Craterellus cornucopioides 

 has peculiar black funnel-shaped fructifications. 



2. The fructifications of the Clavarieae form erect whitish or yellow-coloured 

 bodies, either fleshy and club-shaped or more or less branched, in a coral-like 



fashion. The larger, profusely- branched 

 forms of this group are highly esteemed 

 for their edible qualities ; in particular, 

 Clavaria flava, whose fleshy, yellow- 

 coloured fructifications are often ten centi- 

 metres high, also Clavaria botrytis (Fig. 

 412), which has a pale red colour. Sparas- 

 sis crispa, which grows in sandy soil in 

 Pine woods, has fructifications half a metre 

 in diameter, with compressed, leaf- like 

 branches. 



3. The Hydneae have fructifications 

 with spinous projections over which the 

 hymenium extends. In the simpler forms 

 the fructifications have the appearance 

 of incrustations, with spinous outgrowths 

 projecting from the upper surface ; in 



other cases they have a stalk, bearing an umbrella-like expansion, from the under 

 side of which the outgrowths depend. The latter form is exhibited by the edible 

 fungi Hydnum imbricatum, which has a brown pileus 15 cm. wide, with dark scales 

 on the upper surface, and Hydnum repandum (Fig. 413), with a yellowish pileus. 

 4. In the Polyporeae, a group containing numerous species, the stalked or 

 sessile and bracket-shaped fructifications are indented on the under side with pit- 



FIG. 413. Hydnum repandum. (Reduced.) 



