The analysis of plant root responses to nutrient concentration, soil volume and neighbour presence: Different statistical approaches reflect different underlying basic questions

During fieldwork to assess the status and ecology of Physcomitrium eurystomum Sendtn. in Britain, a naturally occurring sporophytic hybrid was found involving female Physcomitrium patens (Hedw.) Mitt. and male P. eurystomum, previously given the invalid name Physcomitrella amanni Głow. nom. nud. Recent authors have usually placed P. patens in Physcomitrella Bruch & Schimp. or hanorrhegma Sull., but Medina et al. (2019) show both are synonymous with Physcomitrium. Hill et al. (2006) comment Physcomitrella × hampei Limpr. is usually interpreted as Physcomitrium patens × P. eurystomum, for example by Frey et al. (2006), but the protologue for P. × hampei clearly describes parentage as female P. patens and male P. sphaericum (Limpricht 1885), as stated correctly by various subsequent authors, such as Britton (1895), Györffy (1907) and Nieuwkoop (2016). The purpose of this note is to provide a valid name and description for the sporophytic hybrid Physcomitrium patens × P. eurystomum, and to describe its differentiation and designate a type. Turland et al. (2018) is followed for nomenclatural guidance.