Bryum

Bryum is a genus of mosses in the family Bryaceae. It was considered the largest genus of mosses, in terms of the number of species (over 1000), until it was split into three separate genera in a 2005 publication. As of 2013, the classification of both "Bryum" and the family Bryaceae to which it belongs underwent significant changes based on DNA studies.
Description.
"Bryum" is a polyphyletic genus that has high morphological variation. Bryum species generally have shorter laminal cells with short, thick, and rounded stems. All "Bryum" species exhibit narrowed cells at the margins. Bryum species can be identified through patterns of asexual reproduction, coloration features of the stem and leaf base, and the strength of the leaf border.
History.
The genus was described by Johann Hedwig in 1801, with the name being derived from the Greek word for moss.
Botanist John R. Spence published a reclassification of the genus in 2005. The genus "Ptychostomum" was reinstated, while the genera "Leptostomopsis", and "Plagiobryoides" were created. The genera "Gemmabryum", "Imbribryum", and "Rosulabryum" were later published to further divide "Bryum".