Phylum Inophyta [137 



Order 6. Exoascalea [Exoascales] Bessey in Univ. Nebraska Studies 7 : 305 ( 1907) . 

 Suborder Protodiscineae Engler in Engler and Prantl Nat. Pflanzenfam. I Teil, 



Abt. 1: V (1897), not based on a generic name. 

 Order Protodiscineae Campbell Univ. Textb. Bot. 166 (1902). 

 Order Agyriales Clements and Shear Gen. Fung. ed. 2: 141 (1931), in part. 



Ascomycetes parasitic on plants, producing no fruits but a broad layer of asci 

 directly on the mycelium. 



The leaves of the hosts of these parasites become swollen and distorted; the 

 diseases recognized by these symptoms are called curly-leaf diseases. The most 

 familiar is the curly-leaf of peaches, caused by Taphrina {Exoascus) deformans. 

 Many others are known. The agents of all of these diseases may be regarded as a 

 single family Exoascacea [Exoascaceae] Schroter (in Engler and Prantl, 1894), and 

 all are commonly treated as a single genus, Taphrina Fries, typified by T. aurea on 

 poplar trees; there are differences among them which might well be treated as of 

 generic rank. 



Clements and Shear associated the curly-leaf parasites with a collection of sapro- 

 phytes producing small and undifferentiated disk-like or indefinite fruits, as Pyro- 

 nema, Ascocorticium, and Agyrium; and offended against the principles of nomen- 

 clature by re-naming the order Agyriales. It is probable that something of the nature 

 of Agyrium may represent the transition from order Cupulata to this one. 



Martin (1940) described the cytology of Taphrina deformans. The mycelium 

 grows between the cells of the host, not penetrating them. It is a dikaryophase 

 mycelium, the cells binucleate, the nuclei dividing concurrently, cell division occur- 

 ring in such fashion as to separate the daughter nuclei of each pair. In preparation for 

 reproduction, hyphae of short round cells form a single layer between the epidermis 

 and the cuticle of the host. In each cell of these hyphae, the nuclei unite and then 

 divide. The division is mitotic, the fusion nuclei and the daughter nuclei having 

 each eight chromosomes. The cell divides, by a wall parallel to the surface of the 

 leaf, into two. The daughter cell which lies against the tissues of the host dies, 

 and its wall becomes empty; the other cell grows and bursts through the cuticle of 

 the host and becomes an ascus. Its nucleus divides three times; the first two divisions 

 are the meiotic process, and the chromosome number is reduced to four. Cytoplasm 

 accumulates around each of the resulting eight nuclei and is presently cut out by a 

 membrane and a wall. No centrosome is evident at any stage of the process. The 

 spores germinate by sending out buds, as yeasts form buds; sometimes they do this 

 before being discharged from the ascus. So far as Martin could determine, the 

 binucleate condition of the mycelium is established by division of the nucleus of 

 the spore from which it grows. 



Order 7. Sclerocarpa [SclerocarpiJ Persoon Syst. Meth. Fung, xii (1801). 



Order Pyrenomycetes Fries Syst. Myc. 2:312 (1822); order Uterini, suborder 



Pyrenomycetes Fries op. cit. 1: li (1832). 

 Family Pyrenomycetes Fries Epicrisis 1 (1836). 

 Order Pyrenomycetes, suborders Hypocreaceae, Sphaeriaceae, and Dothideaceae, 



Winter in Rabenhorst Kryptog.-Fl. Deutschland 1, Abt. 2: 18, 82, 152, 893 



(1887). 

 Suborder {Unterreihe) Pyrenomycetineae, sub-suborders [Unterordnungen) 



Hypocreales, Dothideales, and Sphaeriales Engler in Engler and Prantl Nat. 



Pflanzenfam. I Teil, Abt. 1: v, vi (1897). 



