Brachythecium Schimp.

Plants slender to robust, forming loose or compact mats, or erect turves. Stems prostrate or ascending, irregularly to subpinnately branched, lacking paraphyllia, in cross-section with a central strand, lacking a hyaloderm (in N.Z. spp.). Stem and branch leaves usually somewhat differentiated, crowded, erect-spreading, sometimes homomallous to ± falcate-secund, symmetric, usually little differentiated when dry, narrowly lanceolate to broadly ovate, acute to piliferous, usually plane, not bordered, serrulate or less commonly entire. Costa single, unbranched, extending half or more of the leaf, occasionally subpercurrent, with or without a terminal abaxial spine (or teeth). Upper laminal cells smooth, firm-walled, elongate, sometimes weakly porose; basal cells shorter and usually ± porose; alar cells usually well differentiated, quadrate to inflated.

Sexuality variable. Perichaetial leaves mostly acuminate, becoming larger with age and/or with fertilisation, erect or widely squarrose-spreading. Setae elongate, straight or flexuose, scabrose or smooth, usually red-brown; capsules inclined to horizontal, rarely ± erect, weakly asymmetric, oblong-ovoid and rather short, or rarely ± cylindric, only slightly wrinkled when dry; exothecial cells variable in shape. Annulus usually differentiated; operculum conic, blunt or acute, rarely apiculate. Exostome teeth yellow-brown to dark brown, cross-striate below, bordered, trabeculate; endostome free, with a high basal membrane; segments well developed, keeled, perforate; cilia variable in number, well developed and nodose to appendiculate, rarely rudimentary. Calyptra cucullate, smooth. Spores small, smooth, or finely papillose.

A large genus estimated to include more than 200 species (Hedenäs 2002). The genus is worldwide in distribution, with species concentrations in eastern Asia and North and South America; relatively few species occur in tropical regions. Eight species are recognised for N.Z.

Brachythecium is a highly diverse genus and it is presented here in a traditional (Brotherean) sense. The genus has often been divided into subgenera and sections, of which four and five, respectively, were treated by Brotherus (1925), but for the most part more recent authors have resisted raising these infra-generic groupings to generic rank. Smith (2004) applied five sections in his treatment of the 15 British species. Crum & Anderson (1981) suggest that the traditional view of Brachythecium is given meaning by having “short, asymmetric capsules, reddish peristomes, commonly roughened setae, and single costate, biplicate leaves”.

Hedenäs’s (2012) review of the Australian species is founded (with contents virtually unchanged) on an earlier (2002) review, and treats five species occurring in N.Z. It also treats two northern hemisphere species that do not occur in N.Z., as well as the Australian endemic B. latinervium Hedenäs. Hedenäs (1996) compared the last to several species, including B. fontanum Fife, with which it will likely prove synonymous.

Both Smith’s (2004) British flora and Crum & Anderson’s (1981) eastern North American flora discuss five species that also occur in N.Z. Despite the modest number of species accepted in the present eFlora, Crum & Anderson’s (1981) warning concerning the difficulty of the genus is valid in a N.Z. context and deserves repetition here: “This is one of the most difficult of all moss genera. Bryologists sometimes try too hard to name sterile material, even when the species are widespread and even weedy, as many of the Brachythecia are. The differences are often difficult to describe, and no keys work well. On a local-flora basis, sterile scraps can usually be named reasonably well, but there are species that resist taxonomic separation even in good and fertile condition.”

Brachythecium cymbifolium Dixon & Sainsbury is treated here as a synonym of Scleropodium touretii.

Brachythecium subpilosum (Hook.f. & Wilson) A.Jaeger, a species based on a South American (Hermite I.) type, was included as a N.Z. species by Fife (1995), without citation of specimens. This report was founded on A.J. Fife 8340 from the St Arnaud Range (Nelson L.D.; CHR 459810). Further study shows this material is better referred to the relatively common B. salebrosum, and it is not discussed further here.

Brachythecium subpilosum var. angustifolium Allison and B. allisonii Fife are nomenclatural synonyms and both are based on material from Flagstaff Hill (Otago L.D., K.W. Allison 5723, CHR 379104). Further study suggests that this material is best referred to B. campestre, wherein it is discussed.

Brachythecium subplicatum sensu Sainsbury is considered here to be identical to B. fontanum Fife.