206 



INTRODUCTION TO THE STUDY OF FUNGI 



following families : — Xylarieae, Dothideaceae, Melogrammeae, 



Diabrypeae, Valseae, and Eutypeae. 



The Xylarieae possess a very definite stroma, which is 

 either vertical, or pulvinate, or effused ; the 

 perithecia carbonaceous and somewhat im- 

 mersed, and the sporidia coloured brown and 

 unicellular. Xylaria is the typical genus, 

 with an erect, branched, clavate, capitate, or 

 subglobose stroma, which is white and corky 

 within, and usually solid (Fig. 95). The 

 It Ml K perithecia are peripherical, and immersed 

 9a entirely, or partially, in the upper portion 

 of the stroma, on all sides leaving the stem 

 sterile. This stem, sometimes very short, 

 sometimes very long, may be smooth or hairy, 

 but it is always surmounted by a fertile head, 

 dotted with the ostiola of the circumambient 

 perithecia. In some species the entire fungus 

 scarcely exceeds one-eighth of an inch in 

 length, in others it attains to six inches or 



F xJ^ S s t eo°tTon of more > with a diameter as variable ; and yet 

 portion and ascns throughout nearly two hundred species the 



with sporidia. , . , ,, , ■, 



essentials are the same — an erect poly- 

 morphous stroma, white and corky within, and a peripherical 

 series of immersed, or semi-immersed, perithecia, enclosing 

 brown continuous or unicellular sporidia. At first, and 

 before the perithecia are fully formed, the apex of the 

 stroma is usually pruinose, with pulverulent minute colourless 

 conidia. The species, with few exceptions, grow on rotten 

 wood, in damp situations, in almost all the countries of the 

 world, wherever a timber tree can flourish and decay. In 

 Thamnomyces. the stroma is reduced to long black threads, 

 upon which the perithecia are clustered or scattered. In 

 BJwpalopsis the clubs are densely caespitose, with a short stem, 

 or crowded upon a very much branched common stroma. In 

 Poronia the stroma is almost pezizaeform (Fig. 96), with the 

 perithecia immersed in the disc, whilst in Camillea the stroma 

 is subcylindrical and truncate, with the perithecia vertically 

 immersed about the apex. In Daldinia the stroma is sub- 



