Haplomitrium minutum (E.O.Campb.) J.J.Engel & R.M.Schust.
Steereomitrium minutum E.O.Campb., Mem. New York Bot. Gard. 45: 569. 1987.
Haplomitrium hookeri var. minutum (E.O.Campb.) Barthol.-Began, Bryophyt. Biblioth. 41: 230. 1991.
Haplomitrium minutum (E.O.Campb.) J.J.Engel & R.M.Schust., Bryologist 97: 65. 1994.
Holotype: New Zealand, North Is., Performance trial plots, Turf Research Institute, nr. Palmerston North (non vidi); isotypes: (MPN [“duplicate of MPN 16015”]!, NY!).
Plants variable, the leafy shoots isophyllous or feebly anisophyllous (leaves of one row may be somewhat narrower), arising from a prostrate, branched, colorless rhizome; rhizomatous system covered by a mucilaginous sheath; leafy shoots erect, unbranched above, yellow-green to green, to 3 mm high. Leaves transversely inserted, ca. 1.4 mm wide, ca. 2 mm long (Campbell, 1987a) unistratose except for a 2(3)-stratose median-basal field, the shape variable (even on one shoot): often ovate to narrowly elliptic to linear or (occasionally) orbicular to subrhomboidal; apices narrowly rounded to bluntly acute to subacuminate, sometimes with a few sessile slime papillae; margins mostly entire, sporadically with 1–2 blunt teeth (margin then ± repand-dentate), the margins with a few sessile slime papillae; cells in median sector 24–36 × 38–55 µm; oil-bodies (Campbell, 1987a) mostly 11–21 per cell, finely granular, ellipsoidal, 2.6 × 4 µm.
Plants dioecious. Androecial plants with antheridia numerous in a terminal cluster or loosely scattered on stem: some axillary (and then up to 5 in an ill-defined zone and not restricted to bract axils), others freestanding; antheridia golden, the stalk massive, 6–8 cells high; axillary antheridia often accompanied by a slime cell at summit of a stalk of ca. 4 cells, other slime cells on a unicellular stalk and inconspicuous, the axillary antheridia occasionally also accompanied by narrowly attenuate scales. Gynoecial shoots (fertilized) with leaves abruptly enlarging toward summit, linear to narrowly ovate toward shoot base, the crowded bracts at summit of shoot a mixture of highly diverse shapes: innermost ones elongate-narrowly elliptical to lanceolate, these surrounded by a “rosette” of larger ones that are subrotund to broadly obovate but abruptly narrowing distally and forming a broadly apiculate to rounded projection; bract margins smooth, never repand-dentate. Sporophyte protective device a true calyptra, the calyptra translucent, smooth, unistratose (at least distally), the cells leptodermous.
Capsule oblong, the wall delicate, uniformly unistratose (except 2[?3]-stratose in apical area), 28–32 µm thick, formed of irregularly oriented (not tiered), oblong to linear cells usually with somewhat oblique end-walls, the cells with exceedingly thin, hyaline walls, in cross section cells convex on both free sides; cells 15–18 µm wide × 38–48 up to 64–72 µm long, each with a single (rarely two) longitudinal, brownish, narrow (2–2.4 µm wide) thickening band in form of an elongated complete ring, or sometimes incomplete at the ends.
Spores (23)26–32 µm, brown, the spore wall verruculate, the verruculae sparingly fused. Elaters 1-spiral, becoming bispiral at tips.
Distribution and Ecology : Known from only one source. Campbell (1987a) stated that it occurred as a weed in Leptinella maniototo turf at Cashmere Bowling Club’s bowling green in Christchurch. Samples of that turf were grown in performance trial plots at the Turf Research Institute near Palmerston North. According to Campbell (1987a) the source of the Leptinella plants is likely to have been Dunback, Otago. David Havell (pers. comm., 2006) who worked with the Leptinella pot-trials at Palmerston North believes that the Haplomitrium occurred in pots of Leptinella dioica “Pahia form,” a cultivar in widespread use for bowling greens, and that this form originates from Southland coastal turflands.
