PYRENOMYCETES. 



129 



Sub-Family 2. Sphaeriales. 



To this sub-family belong the majority of the Pyrenomycefces. 

 The perithecia are of afirm consistence (tough, leathery, woody or 

 carbonaceous), and of a dark colour. Their covering is quite dis- 

 tinct from the stroma when this structure is present. The stromata 

 are sometimes very large, and may be either cushion-like, crus- 

 taceous, upright and club-like, or branched bodies. In general, 

 small, inconspicuous Fungi, living on dead vegetable matter, 

 sometimes parasites. Free conidiophores and conidiocarps are 

 known in many species, and in several, chlamydospore-like forms 

 of reproduction. Orders 3-18 constitute the Sphasriacese of older 

 systematists. 



I 



FIG. 120. Strtc7:eria obduccns : a a portion of an Ash-branch with the bark partly thrown 

 off; on the wood are numerous black perithecia (x 20); b longitudinal section through a 

 perithecium ; c a spore : d longitudinal section through a pycnidium whose ascospores 

 are being ejected ; e portion of the same, with hyphse and spores. 



Order 1. Sordariaceae. Fungi living on dung with fragile perithecia, 

 either aerial or buried in the substratum. The dark brown or black spores have 

 either a mucilaginous envelope (Sordaria, etc.) or mucilaginous appendages (Podo- 

 spora), by means of which their expulsion and distribution are promoted. 



Order 2. Chsetomiaceae. Perithecia fragile, free, bearing on the summit a 

 tuft of hairs. Chcetomium, on decaying vegetable matter. 



Orders 3-7. PcritUecia scattered or aggregated, situated from the commence- 

 ment on the surf ace of the substratum. Stroma wanting. 



Order 3. Trichosphaeriacese. Trichosph^ria parasitica (Fig. 121), on 

 Abies alba ; Herpotrichia nigra on Picea excelsa and Pinus montana. 



