336 THE FUNGI WHICH CAUSE PLANT DISEASE 



Key to Genera of Coleosporiaceae. 



Basidiospore spindle-shaped 1. Ochropsora, p. 336. 



Basidiospore ellipsoid 

 Teliospores in a single layer 

 Teliospore layer strongly arched, form- 

 ing minute knobs 2. Mikronegeria. 



Teliospore in a flat crust 3. Coleosporium, p. 336. 



Teliospores in a double layer, long- 

 stalked 4. Chrysopsora. 



Teliospores in a columnar mass 5. Trichopsora. 



Ochropsora Dietel 



II. Urediniospores solitary. 



III. Teliospores in a waxy crust, loosely united, originally 

 1-celled, later 4-celled, each cell bearing a single basidiospore on 

 a simple sterigma. 



0. sorbi (Oud.) Diet. 



1. .^ciospores {=M. leucospermum) on anemone. 

 II and III. Urediniospores on Sorbus and Spirea. 



Coleosporium Leviell6 



0. Pycnia flattish, linear, dehiscent by a slit, without ostiolar 

 filaments. 



I (=Peridermium). ^Ecia erumpent, definite. Peridium color- 

 less with verrucose walls. Spores globose to oblong, with colorless 

 walls, the outer part formed of densely packed, deciduous tubercles. 



II. Uredinia erumpent, definite, without peridium. Spores 

 catenulate, globoid to oblong, pulverulent; wall colorless, closely 

 verrucose, pores obscure. 



III. Telia indehiscent except through weathering, waxy, some- 

 what indefinite, usually roundish. Spores sessile, 1-celled (by 

 early division of the contents appearing 4-celled) ; wall smooth, 

 colorless, thickened and gelatinous at apex. 



The genus is usually heteroecious. Arthur ' lists some twenty- 

 four species for America. 



There are many biologic forms, morphologically indistinguish- 



