174 Robinson . — Notes on the Genus Taphrina . 
T. AUREA (Pers.), Fries. 
Erineum aureum , Persoon, Synop. Method. Fungorum, 
p. 700. 
Taphrina populina , Fries. 
Exoascus Populi , Thiimen, in Hedwigia, Band xiii. 
p. 98. 
Exoascus aureus , Sadebeck, Untersuchungen liber die 
Pilzgattung Exoascus . 
The only form of this species yet found in America attacks 
the fertile catkins of poplar trees. It is of frequent occurrence, 
and has often been collected on Populus grandidentata, Michx., 
in Massachusetts, at Springfield, Newton, and elsewhere. In 
the infected catkins several of the ovaries grow abnormally 
large, and, late in April or early in May, when the fungus 
reaches its fruiting stage, become golden-yellow from the 
orange-coloured asci of the parasite. The mycelium is only 
subcuticular, and does not enter the inner tissues of the host ; 
each ascus, however, sends down an irregular rootlike process 
20-40 jx long, which, making its way between the cells of the 
epidermis, even enters a little distance the hypoderm below. 
The entire length of the ascus, the process included, is 80-1 14 
and the thickness 16-19 /x. These measurements do not differ 
very much from those of Sadebeck, but Johanson, in describing 
the Swedish form which occurs on the leaves of P. nigra , L., 
gives the total length of ascus as only 47-49 The spores 
are very numerous and of minute size. 
T. CAERULESCENS (Mont, et Desm.), Tub, in Ann. des 
Sciences Nat., ser. 5, Tome v. 
Ascomyces caerulescens , Mont, et Desm., Ann. des 
Sciences, ser. 3, Tome x. p. 146. 
Exoascus caerulescens , Sadebeck, Untersuchungen liber 
die Pilzgattung Exoascus. 
Ascomyces Quercus , Cooke, in Ravenel’s Fungi Amer. 
No. 72. 
This is one of the most common and wide-spread species of 
the genus. It occurs on a number of our American oaks, 
