A Novel Method of Ascospore Discharge

Abstract

It has been generally observed that ascospores are discharged commonly from the apex of the ascus which ruptures at this point just before the ascospores are liberated. A few forms, such as Claz,iceps, have also been reported where the ascospores are discharged through the lower end of the ascus when it is torn from the perithecial base. A still different method of ascospore discharge, however, has recently been observed in certain Pyrenophora species. These have developed on the leaves and stems of Bromus and Agyropyron repens which earlier showed Helminthosporiun lesions and are regarded as the perfect stages of these Helminthosporium species. Pleospora herbarum (Pers.) Rab., studied on various hosts has shown the same phenomenon. In these cases, the ascospore discharge is preceded by a modification of the ascus and the spores are then liberated from the side of the ascus.