256 



THE FUNGI WHICH CAUSE PLANT DISEASE 



Of the some one hundred twenty species D. citri N. is of in- 

 terest since it forms cankers on orange trees in Brazil. 



Didymosphaeria Fuckel (p. 251) 



Perithecia inunersed, later enunpent; asci cylindric to clavate, 

 8-spored; spores elliptical to ovate, 2-celled, brown. 



This genus differs from Didymella chiefly in the dark-colored 

 spores. It contains some one hundred twenty species and has 

 occasional parasitic representatives on leaves and twigs. 



Fig. 186.— Didymella. A, 

 ascus; B, hymenium of 

 a pycnidium. After 

 Brefeld. 



Fig. 187. — Didyipo- 

 sphxria. C, an as- 

 cus; D, con idio- 

 phore and conidia. 

 After Brefeld. 



Fig. 188. — Dflo- 

 p h 1 a gramiiiis. 

 J, ascus; K, 

 spore. After 

 Winter. 



D. sphaeroides (Pers.) Fr. is on Populus leaves in Europe. 



D. catalpse.'^^ 



Perithecia very small, scattered, embedded in the tissue of the 

 leaf, pyriform to nearly spherical, varying in width from 48-104 n 

 and in depth from 64^140 ii; ostiole broadly conical, erumpent; 

 asci 8-spored, cylindrical, usually somewhat curved; paraphyses 

 few or wanting; spores oblong-elliptical, hyaUne or yellowish, 

 uniseptate, constricted in the middle, 9.6-13 x 3-4 fi. On Catalpa. 



D. populina Vuill., causes death of poplars in Europe.''" 



D. epidermidis Fr. is found on Berberis, Sambucus and Salix. 



Gibbellina Passerina (p. 251) 



Stromata black, sunken in the substratum, formed of thin, closely 

 interwoven hyphae; perithecia sunken in the stromata., globose; 



