BFNA Title: Straminergon
XXX. STRAMINERGON Hedenäs, J. Bryol. 17:
462. 1993 *
Plants medium-sized, pale or whitish green to yellow-green. Stem sparsely and irregularly branched, with central strand and without hyalodermis, inner cortical cells thin-walled; outer pseudoparaphyllia broad, triangular to irregular in outline; rhizoids or rhizoid initials at various points on the leaves, or on scattered points or in rows on the stem; axillary hairs with 1--2 distal hyaline cells. Stem leaves straight, ovate or narrowly ovate, distally suddenly narrowed to a rounded and often cucullate apex, not plicate, concave; margin entire; costa single, ending 60--90% way up leaf; median lamina cells incrassate or thin-walled, eporose to porose; alar cells quadrate or shortly to longly rectangular, hyaline or when old brownish, thin-walled or somewhat incrassate, inflated, in ovate or broadly ovate group, distinctly delimited from surrounding cells, decurrent, but often narrowly so. Sexual condition dioicous. Inner perichaetial leaves not plicate; vaginula naked. Capsule curved and ± horizontal; annulus not separating; exostome reticulate on basal outer side, margin distally dentate. Spores 12.5--23 \um.
Species 1 (1 in the flora): widespread.
The genus Straminergon was earlier included in Calliergon. The single member of Straminergon differs from those of the latter genus in its mostly pale green to pale straw-colored shoots and in having markedly smaller and sparsely branched shoots. Further, it has much smaller and sparse axillary hairs and its alar groups are ovate to broadly ovate along the basal leaf margin.
SELECTED REFERENCES Hedenäs, L. 1993. A generic revision of the Warnstorfia-Calliergon group. J. Bryol. 17: 447--479. Hedenäs, L. 2006. Additional insights into the phylogeny of Calliergon, Loeskypnum, Straminergon, and Warnstorfia (Bryophyta: Calliergonaceae). J. Hattori Bot. Lab. 100: 125--134. Janssens, J. A. 1983. Wynne, F. E. 1945. Studies in Calliergon and related genera. Bryologist 48: 131--155.
1. Straminergon stramineum (Dickson ex Bridel) Hedenäs, J. Bryol. 17: 463. 1993
Hypnum stramineum Dickson ex Bridel, Muscol. Recent. 2(2): 172. 1801; Calliergon stramineum (Dickson ex Bridel) Kindberg
Plants whitish to yellowish green. Stem sparsely branched. Stem leaves straight, ovate or narrowly ovate, distally suddenly narrowed to a rounded and often cucullate apex; median lamina cells 40.0-88.0 \um long; alar groups ovate or broadly ovate.
Widespread in mineral-poor to mineral-rich, but not calcareous, and nutrient-poor to -rich fens, shores, or irrigated rocks; low to high elevations; Greenland; Alta., B.C., Man., N.B., Nfld. and Labr., N.B., N.J., N. Mex., N.S., N.W.T., Nunavut, Ont., P.E.I., Que., Sask., Yukon; Alaska, Calif., Colo., Conn., Idaho, Mass., Mich., Minn., Mont., N.H., N.Y., Ohio, Oreg., Pa., Va., Vt., Wis., Wash., Wyo., Utah; South America; n Eurasia; Africa; Pacific Islands (New Zealand); Australia.
Straminergon stramineum is usually easy to recognise due to its pale and sparsely branched shoots and its oblong, ovate, or narrowly ovate leaves with rounded apices. This is one of the Calliergonaceae in which the rhizoid initial cells close to the leaf apex frequently produce rhizoids, which can then be seen as small brownish tufts from some leaves. Occasionally, S. stramineum is confused with the autoicous Calliergon cordifolium in the field. However, small modifications of the latter with comparatively narrow leaves have indistinctly delimited, large alar groups which reach from the leaf margin to the costa or almost so, whereas the alar groups of S. stramineum are well delimited and ovate or broadly ovate along the basal margin. For the differences between S. stramineum and Sarmentypnum sarmentosum, see the note after the latter.