Bartramiopsis
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Authority
Smith, Gary L. 1971. Conspectus of the genera of Polytrichaceae. Mem. New York Bot. Gard. 21: 1-83.
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Family
Polytrichaceae
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Scientific Name
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Discussion
Fig. 64.
Holotype: Atrichum lescurii T. P. James, Bull. Torrey Club 6: 33. 1875. This distinctive, monotypic genus was merged with Lyellia by Salmon (1901), but apart from the lack of a peristome, Bartramiopsis and Lyellia have little in common. The capsule of Bartramiopsis does not develop the conspicuous disc characteristic of Lyellia and Alophosia, and unlike the strongly dorsiventral, angled capsules of these genera, the fruit of Bartramiopsis is terete and campanulate, like that of the South American Dendroligotrichum dendroides (Hedw.) Broth., although much smaller and with the stomata confined to the gradually tapering apophysis, and not dispersed over the whole exothecium.
The strong convexity of the upper layer of cells of the bistratose leaf lamina suggests both Lyellia and Alophosia. This condition results from the apparent loss of lamellae except for those along the median portion of the leaf, without the loss of the ventral cells, which retain their size and shape. Strongly convex ventral cells are also characteristic of Dendroligotrichum, Microdendron, and a number of Pogonatum species. Compared with Lyellia, Bartreimiopsis is more slender in all its parts, although in this respect it does not differ from Alophosia. As in Alophosia, the stem of Bartramiopsis has an indistinct central strand, composed of only slightly thickened hydroids.
Bartramiopsis lescurii has many unique features, among them the sharply serrated lamellae, and the long cilia borne on the margins of the leaf sheath (Fig. 64). Whatever its relationships, Bartramiopsis seems abundantly deserving of its independent generic status.
The distribution of Bartramiopsis (Schofield, 1965; Fig. 90) indicates that it belongs to the group of plants called southern Beringia radiants by Hulten (1937). These distinctly oceanic plants were presumably uniformly distributed over their present Asian and American areas as well as the coast of southern Beringia before the period of maximum glaciation. This area was then broken up by the relatively severe climatic conditions prevailing in Beringia during maximum glaciation. In the case of Bartramiopsis, the old area may have been partially restored by northward radiation in postglacial times.