Distribution, ecology, morphology and reproductive biology of Sphagnum majus in the south of its range (Hautes-Fagnes, Belgium)

Sphagnum majus (Russ.) C. Jens. is a rare dioecious peat moss in its southern range, and in particular, in southern Belgium (Wallonia). Based on original field observations and revision of herbarium material, the distribution of this species in Wallonia is revised and updated. Although it is the most common of the two subspecies, S. majus subsp. norvegicum is reported from Belgium for the first time.The two subspecies are easily differentiated in the field based on macroscopic features, but high levels of variability of microscopic features were observed between the two subspecies in some populations. Sphagnum majus has a very specific niche and is nearly restricted to lithalsas, which are threatened ecological environments in the context of global climatic warming. In Wallonia, male plants of Sphagnum majus subsp. norvegicum are more common than in northern Europe. Capsule production was, however, observed at only one location.