The taxonomic status of Orthotrichum fastigiatum
- Orthotrichum fastigiatum has variously been treated as a species or as subscpecies, variety or even as synonym of O. affine. The distinguishing characters between both taxa were studied. An evaluation revealed that some characters such as spore size (different but intergrading), exostome ornamentation, leaf apex, shape of papillae and lid cannot be used for differentiation. Other characters of O. fastigiatum such as smaller size, capsules imbedded in the leaves, a naked calyptra, the width of the ribs of the urn and the extend to which the empty capsule is contracted below the mouth are usable but hardly to quantify. The observation of mixed stands as well an apparent different ecology indicates different genotypes. Therefore O. fastigiatum should be regarded as infraspecific taxon of O. affine.