130 



PYRENOMTCETES. 



Order 4. Melanommaceae. Eosellinia quercina lives in the roots of 1-3- 

 year-old Oaks, and destroys the plants. 



Order 5. Ceratostomaceae. 



Order 6. Amphisphaeriaceae. Strickeria olducens (Fig. 120) has brick- 

 like spores, and lives aggregated on the hard branches of Fraxinus. 



Order 7. Lophiostomaceae. 



Order 8. Cucurbitariaceae. Perithecia tufted, at first embedded, then 

 breaking through, often situated upon an indistinct stroma. 



Orders 9-13. The peritheeia remain embedded, and are only liberated by the 

 casting off of the covering layers of the substratum. Stroma wanting. 



Order 9. Sphaerellaceae. The species of Spharella have colourless, 

 bicellular spores. They live upon the leaves of many plants, and develope 

 spherical peritheeia upon the fallen leaves. 



Order 10. Pleosporacese. The conidial-forms of Pleotpnra herbarum and 

 P. vulgaris form a black covering on various plants, known as "smuts." 



cL 



FIG. 121. TricTiospJwm'a jiarositica : a a twig of Alies alba with epiphytic mycelium ; 

 b a leaf with mycelium and sporangia (magnified) ; c a sporangium ( x 60) ; d an ascus 

 with spores ( x 650). 



Venturia ditricha occurs on the underside of dry Birch leaves, and perhaps to 

 this belongs the conidial-form, Fusicladium pirinum, which causes the "Bust- 

 spots " on Apples and Pears. 



Order 11. Massariaceae. 



Order 12. Clypeosphaeriaceae. 



Order 13. Gnomoniaceae. Perithecia, with peak-like aperture. Gnomonia 

 erythrostoma in the leaves of Prunus avium, which turn brown and do no fall 

 in autumu. 



Orders 14-18. Stroma generally well developed, The peritheeia are embedded 

 in the stroma, but ivhen this is rudimentary, in the substratum. 



Order 14. Valsaceae. Valsa. 



Order 15. Diatrypaceae. Diatrype. 



Order 16. Melanconidaceae. 



Order 17. Melogrammataceae. 



