ORDER TAPHRINALES (eXOASCALES) 243 



etal position assumed by the ascospore nuclei before the spores are 

 dehmited are all pointed to as Basidiomycetous characters. 



Family Ascocorticiaceae. Ascocorticium, the only genus of the 

 Family Ascocorticiaceae, consists of a small number of species whose fruc- 

 tifications produce a gray- or pink-colored thin coating with indeterminate 

 growth, over the surface of bark or bare wood of dead trees. The hypo- 

 thecium consists of four to six layers of interwoven hyphae running par- 

 allel to the surface of the bark. Upon these arise the ovoid eight-spored 

 asci. The asci are formed by the hook or crozier method from dicaryon 

 ascogenous hyphae whose origin is not known. It is not known whether 

 there is any sexual process other than the probable union of tA\ o nuclei 

 in each young ascus. 



Family Taphrinaceae. Ta-phrina {Exoascus, Magnusiella, or Taph- 

 ria) is the only genus of the Taphrinaceae. Of great economic importance 

 is T. deformans (Berk.) Tul., causing the disease of the peach {Amijgdalus 

 persica L.) known as leaf curl. The ascospores or spores arising from them 

 by budding lie dormant in crevices of the twigs or on the bud scales until 

 the following spring when they germinate and infect the young leaves 

 and even the fruits and young twigs. On the other hand the ascospores 

 may also germinate by budding on the surface of the host and grow in 

 the manner of a yeast, infection taking place in the spring from the yeast- 

 like cells. The affected leaves become much thickened and distorted as 

 well as discolored. The diseased fruits may show irregular bright red 

 patches of thickened tissues. On the diseased areas the asci are formed 

 subcuticularly in the late spring or early summer. In a few cases the 

 spores appear to germinate soon after formation so that Waite (1932) 

 and Poole (1932) report what may be a secondary infection occurring 

 the same season. Taphriria pruni Tul. and T. communis (Sadeb.) Giesenh. 

 infect the young fruits of Prunus and Padus, causing them to develop into 

 the hollow hypertrophied structures which, upon the plums, are known 

 as "plum pockets." Here also the asci are subcuticular. T. cerasi (Fckl.) 

 Sadeb. causes witches' brooms on various species of cherry {Prunus cerasus 

 L., P. avium L., etc.). The mycelium lives perennially in the tissues of 

 the host. T. robinsoniana Giesenh. causes hypertrophy of the scales of 

 the aments of the alder (Alnus). In T. potentillae (Farl.) Johans., the 

 mycelium lives beneath the epidermis and sends up, between the epi- 

 dermal cells, branches which bear separate asci. (Fig. 86.) 



In this family the whole vegetative mycelium consists of dicaryon cells 

 and is therefore comparable to the ascogenous hyphae of those forms 

 with definite sexual organs and Avell-developed apothecia, such as Pyro- 

 nema, etc. Many authors consider this family to be primitive, but it seems 

 more logical to consider it as a much simplified offshoot of the Pezizales, 

 the Ascocorticiaceae being a possible intermediate stage. Miss Catherine 



