Tropicos | Name - Weissia Hedw.

Weissia Hedw.

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Project Name Data (Last Modified On 10/22/2013)

Acceptance : Accepted

Note : By Richard H. Zander

Project data (Last Modified On 10/22/2013)

Discussion: The genus, characterized most generally by involute leaf margins, consists of three sections corresponding to degrees of sporophytic reduction: The sect. Weissia shows exserted, operculate capsules with a fairly well-developed peristome. The sect. Hymenostomum lacks a peristome, and the mouth of the capsule, on dehiscence, is covered by an evanescent membrane formed by inner cells of a usually thick capsule wall. The sect. Astomum usually has a short seta, an ovoid to globose, irregularly dehiscent capsule, and no peristome. Weissia differs from Trichostomum in its generally monoicous sexual condition and leaf margins usually incurved or involute. Although Weissia jamaicensis is dioicous, its gametophyte is like that of the monoicous species. Two of the species (now in different sections of the genus) with plane leaf margins, W. sinaloensis and W. planifolia, may be part of a reduction series from an ancestor rather like Trichostomum brachydontium and not from the presumed Weissia jamaicensis-like progenitor of species with usually incurved margins.

Reference Source:

Sharp, A. J., H. A. Crum & P. M. Eckel. 1994. The moss flora of Mexico. Mem. New York Bot. Gard. 69(in 2 parts): [i]–vii + 1–580 + I–XVII; [i]–viii + 581–1113 + I–XVII.