[A Splachnum-like moss with bryoid leaves]

William D. Reese

Plants gregarious to tufted, mostly small and soft. Stems erect, mostly undivided, epidermis of a few layers of large cells with slightly thickened walls surrounding a few layers of cells with thinner walls, both layers chlorophyllose and with yellowish walls; central cylinder of thin-walled cells, central strand undifferentiated to present and distinct, medial stem cells sometimes fragmenting and leaving a void; axillary hairs 2--3-celled, proximal cell(s) short, with faintly yellowish walls, distal cell much larger. Leaves oblong to obovate-spatulate, rarely bordered with elongate cells, margins plane to recurved, mostly crenulate distally, sometimes entire, apex rounded; costa single, short to elongate, ending at midleaf to percurrent or shortly excurrent, in cross section showing 0--2 guide cells, one stereid band of 1--5 stereid or substereid cells, with epidermal cells on both surfaces; medial cells of leaves oblong, smooth or occasionally distinctly mammillose on one or both surfaces. Specialized asexual propagation by gemmae on axillary rhizoids and by rhizoid tubers. Sexual condition dioicous. Perichaetia lacking, perichaetial leaves not differentiated, archegonia clustered at stem tip, becoming solitary in leaf axils by elongation of stem apex, paraphyses lacking. Seta single, short, smooth. Capsule exserted, erect, symmetric, short-cylindric to obpyriform, with scanty phaneropore stomata at base; annulus of several rows of thick-walled isodiametric to horizontally elongate cells; operculum conic-apiculate; peristome of 16 teeth, set deep inside capsule mouth, the teeth wide-spreading when dry, connivent over the mouth of the capsule when moist. Calyptra elongate, narrowly conic-cylindric, split from base on one side about half its length, scarcely cucullate. Spores spherical.

Species ca. 23 (1 in the flora): tropical and subtropical regions of the world.

Splachnobryum is here treated in the Pottiaceae (W. R. Buck and B. Goffinet 2000), where it has been placed previously, although it has also been treated in the Splachnaceae as well as in the family Splachnobryaceae (T. Arts 2001; A. Koponen 1981). Breen and Pursell (1959), after reviewing specimens of Splachnobryum from the United States, Mexico, Central America, and the West Indies, recognized only S. obtusum. They placed many names into the synonymy of S. obtusum, although apparently without examining the types of all these names.

The species of Splachnobryum commonly grow on basic substrates in moist situations; they are sometimes tufa-forming mosses. Although archegonia are often present in specimens, antheridia and sporophytes are uncommon. Identification to the species level usually must be made on sterile specimens, which generally lack well-defined taxonomic characters. As a consequence, much herbarium material must be considered to be only tentatively identified to species. This especially applies to populations in the flora area, which is marginal to the main world range of the genus and where the plants are always sterile. In the absence of reliable and repeatable means to sort specimens from the flora area, they are here all assigned to a single species, S. obtusum. The perigonia are terminal, becoming lateral by innovations, the antheridia maturing asynchronously within each perigonium, surrounded by a few short broad bracts, or the perigonial bracts not much differentiated from vegetative leaves, paraphyses are lacking, and the antheridia are sometimes solitary in leaf axils below the perigonia.

SELECTED REFERENCES

Allen, B. and R. A. Pursell. 2000. A reconsideration of the systematic position of Splachnobryum. J. Hattori Bot. Lab. 88: 139--145. Buck, W. R. and B. Goffinet. 2000. Morphology and classification of mosses. In: A. J. Shaw and B. Goffinet, Bryophyte Biology. U.K. Ch. 3, pp. 71--123. Koponen, A. 1981. Splachnobryaceae, a new moss family. Ann. Bot. Fennici 18: 123--132. Reese, W. D. 1998. Splachnobryum in North America north of Mexico. Evansia 15: 125--130.

OTHER REFERENCES

Andrews, A. L. 1949. Taxonomic notes. IX. Splachnobryum kieneri. Bryologist 52: 78--83.
Arts, T. 1996. The genus Splachnobryum in Africa, with new combinations in Bryum and Gymnostomiella. J. Bryol. 19: 65--77.
Arts, T. 2001. A revision of the Splachnobryaceae (Musci). Lindbergia 26: 77--96.
Breen, R. S. and R. A. Pursell. 1959. The genus Splachnobryum in the United States, Mexico, Central America and the Caribbean. Rev. Bryol. Lichénol. 38: 280--289.
Chopra, R. N. and A. Rashid. 1969. The archegonia of Splachnobryum. Bryologist 72: 525--527.
Chopra, R. N. and Sheel. 1974. Some new observations on the gametangia in Splachnaceae. Bryologist 77: 623--628.
Eddy, A. 1996. A Handbook of Malesian Mosses, Volume 3. Splachnobryaceae to Leptostomataceae. London.
Müller, J. A. K. 1869. Splachnobryum, eine neue Gattung der Splachnaceen. Verh. K.K. Zool.-Bot. Ges. Wien 19: 501--506.

Version History forSplachnobryumi:

Version 2: May 2001 -- illustrations added; Splachnobryum moved to Pottiaceae.

Version 1: March, 1999: minor editorial changes

Version 1: February, 1999