SKCT. I 



CRYPTOGAMS 



393 



upon decaying wood, dung, etc., while a few genera occur as parasites ujion the 

 larvae of insects. The flask-shaped fructifications or peritliecia are characteristic 

 of this order. The perithecia are open at the top, and are covered inside, at the 

 base, with a hynienial layer of asci and hair-like jiaraphyses (Fig. 321). The 

 lateral walls are coated with similar hy])hal hairs, the periphyses. The ascospores 

 escape from the perithecia through the aperture. 



The simplest Pyrenomycetes possess free perithecia (Fig. 321) which are usually 

 small and of a dark colour, and grow singly on the inconspicuous mycelium {e.g. 

 Ncdria, S-phacria, and Podospora). In other cases the iierithecia are in groups 



embedded in a cushion- or club-shaped, 

 sometimes branching, mass of compact 

 mycelial hyphae having apseudo-parenchy- 

 matous structure. Such a fructification is 

 known as a stroma. 



In the life-history of most Pyrenomy- 

 cetes the formation of perithecia is preceded 

 by the production of various accessory 

 fructifications, particularly of conidia, 

 which are abstricted in different ways. 



::4^"'«>g^^ 



Fio. 321. — Perithecium of Podospora fimiseda 

 in longitudinal section, s, Asci ; n, 

 parapliy.ses ; e, periphyses ; m, mycelial 

 hyphae. (After v. Tavel, x 90.) 



Fio. 322. — 1, Conidiophore abstricting conidia, 

 from a pycnidium of Cryptospora hypodermia. 

 (After Brefeld, x 300.) 2, Pycnidium of .S(ric- 

 kcria ohdticens in vertical section. (After 

 TULASNE, X 70.) 



either directly from the hyphae or from special conidiophores, and assist in 

 disseminating the fungus. The conidiophores are frequently united in distinct, 

 couidial fructifications. A special form of such fructifications are the pycnidia 

 produced by many genera. They are small spherical or flask-shaped bodies which 

 give rise to branched hyphal filaments from the apices of which conidia, in this 

 case termed PYCNosruREs or pycnoconidia, are abstricted (Fig. 322, 1, 2). The 

 structure of the pycnidia and pycnospores corresponds to that of the spermogonia 

 and spermatia of the Lichens, and they may in part at least be regarded as male 

 organs. 



Claviceps puipurca, the fungus of Ergot, is important on account of its 

 official value. It is parasitic in the young ovaries of different members of the 

 Gramineae, particularly of Rye. The ovaries are infected in early summer by 

 the ascospores. The mycelium soon begins to form conidia, which are abstricted 

 in small clusters from short lateral conidiophores (Fig. 323, A). At the same 

 time a sweet fluid is extruded. This so-called honey-dkw is eagerly sought by 



