Haplomitrium minutum

Detailed description

Plants variable, the leafy shoots anisophyllous or feebly so (leaves of one row may be somewhat narrower), arising from a prostrate, branched colourless rhizome; rhizomatous system covered by mucilaginous sheath; leafy shoots erect, unbranched above, yellow-green to green, to 3 mm high. Leaves transversely inserted c.1.4 x 2.0 mm unistratose except for 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, the margins with a few sessile slime papillae; cells in median sector 24-36 × 38-55 micrometre; oil-bodies mostly 11-21 per cell, finely granular, ellipsoidal, 2.6 × 4.0 micrometre. 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 c.4 cells, other slime cells on a unicellular stalk and inconspicuous, the axillary antheridia occasionally accompanied by narrowly attenuate scales. Gynoecial shoots (fertilised) with leaves abruptly enlarged toward summit, linear to narrowly ovate toward shoot base, the crowded bracts at the summit of shoot a mixture of highly diverse shapes: innermost ones elongate-narrowly elliptical to lanceolate, these surrounded by a rosette of large 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, 28-32 micrometre thick, formed of irregularly orientated (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 × 38-72 micrometre, each with a single (rarely two) longitudinal, brownish, narrow (2.0-2.4 micrometre wide) thickening band in form of an elongated complete ring, or sometimes incomplete at the ends. Spores 23-32 micrometre, brown, the spore wall verruculate, verruculae sparingly fused. Elaters 1-spiral, becoming bispiral at tips.