328 Bulletin 73. 



Prunus pennsylvanica L. Wild Red Cherry. 

 Exoascus insititi(zS2i&eb. 



I have referred to this species, specimens collected by Seymour 

 at Temple, N. H., June 16, 1888, on the leaves of Prunus penn- 

 sylvanica ly. It was distributed as Taphrina deformans (Berk.) 

 Tul., in Seymour and Earle's Economic Fungi, No. 15. The 

 specimen in the collection to which I have had access shows 

 several small twigs curved to one side growing from the end of a 

 larger twig. The specimen has very much the appearance of a 

 small "witches broom." The young twigs are pale and slender, 

 and the leaves are not much deformed, the upper surface being 

 somewhat folded, while a large portion of the under surface is 

 covered with the asci which give them a greyish white appear- 

 ance. The mycelium is present in the inner tissue of the leaf but 

 is not nearly so abundant as in the peach. 



The asci are quite regularly smaller than those of E. deformans 

 on the peach. Through the kindness of Mr. J. B. Ellis I have 

 had the opportunit}- of seeing a specimen of this species on P. 

 domestica from Sweden, and the asci are very much nearer those 

 on that specimen than on the peach. In the measurements given 

 by Sadebeck the asci are 25 long by 8-10 in diameter, which 

 agrees quite well with the specimens on P. pennsylvanica, though 

 on the latter some specimens measure 30 long, but the average is 

 near 25. The stalk cells are 6-8 high by 7-9 in diameter and 

 taper in many cases a little below, and then frequently intruding 

 slightly between the cells of the epidermis. The measurements 

 given for the stalk cells by Sadebeck are slightly larger, being 8 

 high by 8-10 in diameter. Aside from these slight variations it 

 agrees very well with Sadebeck' s species. It was first described 

 by Sadebeck* from specimens on Pritnus insititia and was later 

 found by him on Prunus domestica. It forms " \^tches brooms" 

 on both these trees in Europe. 



*Unters. ii. d. Pilzgattung Exoascus etc. Abgedruck. a, d. Jahrb. d. Hamb. 

 Wiss. Anst. p. 113, 1884. 



Kritische Unters. ii. d. durch Taphrina-Arten etc. Ibid, VIII, p. 27, 1891. 



Die parasitea Exoasceen. Ibid, X, 2, p. 48, 1893. 



