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Published In: The Bryologist 47(1): 4. 1944. (Bryologist) Name publication detail
 

Project Name Data (Last Modified On 3/8/2011)
Acceptance : Accepted
Project data     (Last Modified On 3/8/2011)
Discussion:

Macrocoma is a genus of slender species with widely spaced branches, and leaves stiffly erect‑appressed when dry. Macromitrium, Groutiella and Schlotheimia differ from Macrocoma in having leaves variously twisted‑contorted or incurved when dry. The leaf cells in Macrocoma are rounded to elliptic throughout and although the basal cells can be unipapillose or strongly mammillose they are never tuberculate. Schlotheimia and most species of Macromitrium differ from Macrocoma in having linear basal leaf cells, most Macromitrium species also differ in having  tuberculate basal leaf cells. Groutiella also has rounded, mostly non-tuberculate basal leaf cells, but it differs from Macrocoma in having a basal border of linear cells.

The capsules in Macrocoma can be smooth or furrowed, however capsule furrowing is so variably expressed – even within single collections – that the feature is of uncertain taxonomic value in the genus. Peristome form is often given considerable taxonomic weight in the genus despite the fact that all Macrocoma peristomes are reduced or rudimentary. Macrocoma was revised by Vitt (1973a, 1980).

Macrocoma is often treated as neuter noun, but it is actually a first declension feminine noun (Eckel 2000).


 

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Macrocoma (Hornsch. ex C. Müll.) Grout, Bryologist 47: 4. 1944.

Plants slender, in reddish brown to olive‑brown mats. Stems creeping, irregularly or subpinnately branched with erect‑ascending branches. Leaves erect‑appressed when dry, weakly keeled, lanceolate, ovate‑lanceolate or ovate; apices obtuse, acute or acuminate; costae strong, percurrent; margins crenulate or entire; cells short, rounded above, rounded to elliptic below, smooth, unipapillose, or mammillose. Setae erect. Capsules exserted, elliptic to oblong‑cylindrical, smooth or plicate; opercula conic rostrate; peristome double, single or absent, exostome teeth usually reduced. Spores large, isosporous, to 50 μm. Calyptrae mitrate to campanulate, variously hairy.

 

 
 
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