THE FUNGI WHICH CAUSE PLANT DISEASE 197 



Perithecia sunken in a fleshy stroma 



Spores not filiform; perithecia half 

 or entirely sunken in the 

 stroma, and distinct from it. . 5. Hypocreea, p. 198. 



Spores filiform; perithecia com- 

 pletely embedded in the 

 stroma and not clearly 'dis- 

 tinct from it 6. Clavicipiteae, p. 199. 



The first tribe contains no parasitic genera while the second and 

 third contain but one each. Of the Hypomycetese, the genus 

 Hypomyces (p. 200) is set off from the others by its 2-celled hyaline 

 fusiform spores, and its cottony stroma. Of the Melanosporese 

 the genus Melanospora (p. 200) is distinguished by the long beaks 

 of its flask-shaped perithecia, which are brown rather than black, 

 and its brown 2-celled spores. 



Keys to the Geneka of Nectrieae, Hypocreeae and Clavicipiteae 



Tribe IV. Nectrieae (p. 196) 



Conidiophores not of the Stilbum type 

 Spores elongate, 1-celled; perithecia free 

 on the substratum; stroma none 

 Spores not appendaged 

 Perithecia yellow or red 

 Asci cylindric; ostiole concolorous 



with the perithecium 1. Nectriella. 



Asci clavate-cylindric; ostiole 



darker than the perithecium. . 2. Thelocarpon. 



Perithecia violet or blue 3. Lisiella. 



Spores appendiculate 4. Eleutheromyces. 



Spores elongate, 2 to many-celled 

 Spares with cross walls only 

 Spores 2-celled 

 Asci 8-spored; often with 1-celled, 

 conidia formed in the ascus 

 Perithecium yellow or red 



Spores hyaline 5. Nectria, p. 201. 



Spores brown 6. Neocosmospora, p. 205. 



Perithecium blue or violet 7. Lisea. 



