The difference is relatively minor, and may be hard to evaluate until one has had some practice at looking at asci from many genera. The way an ascus develops is reflected in the shape of the base of a mature ascus. See the glossary for a discussion of pleurorhynchous, aporhynchous, and acrorhynchous asci. Data on the ascus base has not been recorded for many species, so this feature is of limited use in identifying specimens to genus. Asci that arise from croziers are likely to be pleurorhynchous with either the end cell fused to the antepenultimate cell or free of it.
Paraphyses provide a few characters useful in making identifications.
Paraphyses are more or less distinct in exothecia, ptychothecia, and stereothecia and may be much longer than the asci that the asci never project beyond them. In stereothecia in young specimens one can often find what appear to be young paraphyses but in older specimens they have grown into the hymenium on the opposite side of the cavity and filled it. The green color fades on standing in Melzer's reagent at least to the background color and is not always demonstrable in dried specimens. The majority of taxa have straight paraphyses, but in a few they are regularly strongly curved at the apex. In those cases, especially in exothecia and ptychothecia, where the paraphyses are much longer than the mature asci and form a more or less distinct layer over the asci, the layer is called the epithecium.