Nebraska Forest Fit /////. // 



93 



whitish, pycnidia few, lenticular, minute. Spores rod-shaped, 

 slightly curved, septate, hyaline, 21x2 microns. Quite common 



o;i .-leer iic(/itudo. 



Scptcria ar(j\raea Sacc. 



Discolored spots yellowish, often with a dark margin, on the 

 upper side of the leaf. Pycnidia dot-like, lenticular, clustered. 

 Spores cylindrical, straight or flexuous, hyaline, 25x3 microns. 

 On Elaeagnus argentia. 



Scptoria pruni Ellis. 



Pycnidia in brown deciduous spots, 1-2 mm. in diameter, 

 and immersed in the dead tissue. Spores cylindrical, curved, 



obtuse at the ends, 4-6 septate, 

 40x2 microns. Common on Prunus 

 americana. 

 Other species : 



Scptoria ccrasina Peck, on 

 Prunus scrotina; S. corylina Peck, 

 on Corylus americana; S. cornicola 

 Desm. on Cornus sp'; S. rhoina 

 B. & C. on Rhus glabra; S. sam- 

 bucina Peck, on Sambucus cana- 

 do:sis. 



Leptostromaceae: 



In this family the pycnidia are 

 membranous or sometimes carbon- 

 ous, and usually black in color, 

 more or less distinctly dimidiate or 

 Fig. 21. Leptostroma. a. scutiform, erumpent or superficial. 

 Habit upon the leaf. b. Sec- The pycnidia do not open by a reg- 

 tion of pycnidium. All highly lllar pore but b the breaking open 

 magnified r^i i- 11 r 



of the pycnidium and the formation 



of an irregular narrow or linear cleft. See fig. 21. 



Leptostroma 



Pycnidia dimidiate, flattened, elongate, superficial or sub- 

 cuticular, dark, opening by a more or less irregular cleft. Spores 

 ovoid, oblong or sausage-shaped, continuous, hyaline or very 

 slightly colored. 



Leptostroma hypophylla B. & Rav. 



Pycnidia on the lower side of the leaf, flattened, membranous, 

 1-2 mm. in diameter, thickly scattered over the part of the leaf 



