A Biosystematic Study of Sphagnum capillifolium Sensu Lato

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Abstract
Analysis of herbarium collections of Sphagnum capillifolium sensu lato from eastern North America indicates that taxa within the complex are easily distinguished by spore morphology, but there is considerable overlap among taxa in gametophyte morphology. Uniform common garden studies of gametophytes transplanted from the field, gametophytes raised from spores, and spores that developed on plants during the course of the common garden indicate that there is a genetic basis for three previously recognized taxa considered within S. capillifolium s.l. A woodland taxon, S. subtile, should be recognized as a separate species since it is easily distinguished by gametophyte and spore morphology, in addition to habitat, from the other open bog taxa of S. capillifolium s.l. The open bog taxa of S. capillifolim s.l. examined in this investigation, S. nemoreum and S. rubellum, exhibit considerable overlap in gametophyte morphology in the field and when grown in a uniform common garden. However, they may be distinguished on the basis of spore morphology, which was found to be little affected by environmental factors. These results suggest that the open bog taxa, recognized at the species level as S. nemoreum and S. rubellum by some taxonomists, are better recognized at the varietal level as S. capillifolium var. capillifolium and var. tenellum respectively.