30 IOWA ACADEMY OF SCIENCE 



l-15i". This is the Leptothyriiim Juglandis Eabenh., or Cryptosporium 

 nigrum Bon. The perfect form of the fungus occurs in dead leaves in 

 the spring. The perithecia are brown, spherical 200-300^ with a 

 long beak; each ascus has 8 two-celled, spindle-shaped, colorless asco- 

 spores, 19-25-"x3-«. Klebahn was able to secure positive infec- 

 tious inoculation by sowing the ascospores on young leaves of the 

 English walnut. The fungus can be cultivated very easily in nutrient 

 agar containing a decoction of walnuts. In these cultures an abundance 

 of conidia were produced, also an excretion of calcium oxalate. 



It may be added that I have seen the fungus abundant on the black 

 walnut and butternut in Iowa, Wisconsin, Illinois and Minnesota, and 

 on the black walnut in Missouri. 



The Maple Exoascus {Taphrina). 



During the early part of July, 1908, the writer found a species of 

 Taphrina abundant on the Rocky Mountain hard maple (Acer grandi- 

 dentatum) in the Wasatch mountains near Logan, Utah, especially in 

 Logan canon and along the adjacent streams emptying into the Logan 

 river. In some cases the trees were entirely defoliated, in others a 

 majority of the leaves were attacked. At lower altitudes' the disease 

 was too far advanced to indicate the cause of this abundant epidemic, 

 but at higher elevations the younger leaves had the characteristic pale 

 color above, with a whitish somewhat mealy substance on the under 

 surface, also in some cases the mealy substance was on the upper i?ur- 

 face as well. 



This fungus is of particular interest since no fungus of this group on 

 the maples is common in the United States. Peck^^ described an Asco- 

 myces lethifer upon the Mountain Maple (Acer spicatum). He re- 

 garded this species as very distinct from Taphrina polyspora (Sorok.) 

 Johan., because this species forms definite spots and the leaves soon 

 turn black, wither and die.^^ "Sometimes all the leaves on a branch 

 are affected and the fungus then causes a veritable blight." 



The T. polyspora was described as an Ascomyces (Ascomyces poly- 

 spora Sorok. )^^ and subsequently placed in the genus Taphrina by 



"Rep. N. Y. State Museum. 40:66. 



^Indefinite, hypophyllous, often occupying ttie whole lower surface of tiie 

 leaf and suffusing it witti a glaucous bloom; asci cylindrical, obtuse or subtrun- 

 cate, 40 — 50x15 — 20/^; spores minute, varying from narrowly elliptical to sub- 

 globose, 4 — 5x2 — Sya. 



^Ann. d. Sc. Nat. VI: 4: 72. 1876. 



