Pohlia Hedw.

Plants erect, small to medium-sized, in loose or dense turves, tufts, or scattered among other mosses, dull or lustrous, variably coloured. Stems mostly simple, sometimes forked, or branching by innovation, in cross-section with a central strand, with papillose or rarely nearly smooth rhizoids. Leaves often crowded near the shoot apex, erect or erect spreading when moist, mostly little altered when dry, ovate-lanceolate to narrowly lanceolate or rarely ovate, acute, not bordered, ± toothed near apex or teeth extending c. ½ the leaf; upper laminal cells oblong-rhomboidal to linear, thin- or thick-walled, sometimes narrower at margins but not forming a distinct border, becoming shorter and laxer towards the insertion. Costa usually rather narrow, percurrent, ending below the apex, or rarely excurrent. Axillary gemmae frequent in some species but absent in others, clustered or solitary, bulbous or elongate.

Dioicous, paroicous or rarely autoicous (fide Shaw). Perichaetia terminal, usually with the ♀ leaves enlarged. Perigonia terminal or lacking. Setae usually single, elongate, flexuose and twisted when dry, usually curved or hooked just below the capsule; capsules inclined, pendent, or rarely suberect, ± symmetric, elongate and clavate, pyriform, or sometimes short-ovoid, with a long or short sterile neck; annulus mostly present and revoluble; operculum conic, mammillate, or short-rostrate; stomata superficial or rarely immersed. Peristome double; exostome teeth 16, lanceolate, variable in colour, not or narrowly bordered; endostome arising from a short or tall finely papillose basal membrane, with segments keeled and usually perforate, and cilia either well-developed and nodulose or rarely rudimentary. Calyptra cucullate, smooth. Spores spherical, finely papillose.

Pohlia is a large genus of nearly cosmopolitan distribution, although tropical species occur predominantly at higher elevation and even temperate species are largely confined to mountainous areas. Shaw (in Shaw & Ramsay 2013) considered it to include about 85 species, whereas earlier authors (e.g., Brotherus 1924, as Webera and Mniobryum) considered the genus to include a larger number of species.

Species of Pohlia are most likely to be confused with Bryum, but the present genus has more elongate laminal cells and leaves that lack a distinct border. The costa here nearly always ends in or below the leaf apex, while in Bryum the costa is often excurrent. According to Shaw & Ramsay, no species of Pohlia have appendiculate cilia (with the possible exception of P. nutans) or synoicous perichaetia, both of which are common in Bryum s.l. Confusion could also occur with Mielichhoferia, but the sole N.Z. representative of that genus has basal paroicous or synoicous perichaetia as well as suberect capsules with a single peristome.

There is an inexplicable lack of Pohlia (or Webera and Mniobryum) collections in the T.W.N. Beckett herbarium at CHR.

The family placement of Pohlia has attracted much attention in recent years. The decision to treat Pohlia in the Mielichhoferiaceae follows Shaw & Ramsay’s (2013) treatment of the Australian members. Their placement of the genus here was informed by the study of Cox & Hedderson (2003). Goffinet et al. (2009) and other recent authors, including Smith (2004), have recently treated it as a member of the Mniaceae, while Sainsbury (1955) followed many earlier authors to treat this genus as part of the Bryaceae.

Approximately half of the species of Pohlia occurring in New Zealand are also widespread in the northern hemisphere, and so floristic accounts such as Crum & Anderson (1981), Smith (2004), and Shaw (1981) are useful here. A treatment of Pohlia in South Georgia has been provided by Clarke (1973). Little has been published since Sainsbury (1955) dealing specifically with N.Z. species, with the exception of the key to gemmae-bearing species and the description of P. australis by Shaw & Fife (1985).