A NEW HOST AND STATION FOR 

 EXOASCUS FILICINUS 

 (ROSTR.) SACC. 



W. C. COKER 



On May 14 of this year, I noticed a number of plants of the 

 Christmas fern (Dryopteris acrostichoides) whose fronds were 

 attacked by a fungus, causing well-defined yellowish areas up to 

 a centimeter or more wide on both the sterile and fertile leaflets. 

 The ferns were growing in a deep ravine along the Raleigh Road, 

 Rocky Ridge Farm, Chapel Hill, N. C. Specimens were 

 brought to the N. Y. Botanical Garden, where Mr. F. J. Seaver 

 determined the fungus as Exoascus filicinus (Rostr.) Sacc. 

 (Taphrina filicina Rostr.), and careful dissections and measure- 

 ments made by me showed our parasite to agree in every way 

 with descriptions of that species. The asci do not break through 

 nor push off the epidermis, but form a dense layer on its surface. 

 They are small, averaging about 33 /x long and 5 or 6 /x, wide, and 

 the spores are about 5 /x long and 2 fx thick. 



This Exoascus seems to have been observed heretofore only in 

 Sweden, on Dryopteris spinulosa (Polystichum spimilosum) . It 

 will probably be found in other places in America and on still 

 other species of Dryopteris. 



Chapel Hill, N. C. 



247 



