Revisie van de in Nederland voorkomende soorten van het geslacht Campylopus Brid.

A revision has been made of the genus Campylopus with respect to those species which occur in the Netherlands. The indigenous species in the collections of the herbaria of Leiden, Royal Netherlands’ Botanical Society and those of several small private herbaria were examined. Difficulty was experienced in separating the two species C. fragilis and C. pyriformis, although from a perusal of the literature on this subject no such trouble was expected. A critical study was therefore made of all the distinguishing characters cited in the literature. In the course of this study a fairly large number of specimens of both species were measured as regards form and length of leaves, width of base and nerve, length of lamina and subula, length of seta and peristome, etc. On the basis of these data it was concluded that only the form of the leaf (in casu, the length of the broad leaf-base in proportion to the length of the subula) was of real taxonomic importance. This makes it very doubtful whether both these types can be maintained as species. I therefore regard C. pyriformis as a variety of C. fragilis. There seems to be no valid reason for making C. pyriformis a sub-species of C. ‘ “ ' ” ' flexuosus as was done by Boulay and Dixon. As to the other indigenous species. C. brevipilus fa. epilosus was in several cases not recognized as such by the older bryologists, probably because the importance of the nerve structure was not sufficiently realised at that time. As regards the distribution of the species in the Netherlands, C. subulatus is very rare and has only been found once; C. brevipilus has become rare since the last century, because many of the heaths and moors which form its habitat have in recent times been reclaimed. C. flexuosus and C. fragilis are not uncommon, C. fragilis var. pyriformis (C. pyriformis) is common.