Lembidium Mitt.
Type: Lembidium nutans (Hook.f. & Taylor) Mitt. (≡Jungermannia nutans Hook.f. & Taylor)
Plants strongly anisophyllous, erect, light to whitish green, secondary pigmentation lacking, moderate in size, to 1.6 mm wide, the leafy erect shoots with apices usually decurved, circinate or even hamate. Branching polymorphous: bearing ventral-intercalary, creeping, elongated and interwoven stolons in abundance; leafy branches erect, ventral-intercalary in origin from the felt-like mat of stoloniferous branches, the erect leafy axes sporadically to commonly branching, the branches of the Frullania type or sometimes ventral-intercalary; Frullania -type branches bazzanioid: from one side of axis only; lateral-intercalary branching apparently absent (at least in leafy shoot sectors). Stems of leafy shoots with cortical cells exceedingly large by comparison to leaf cells, the cortical cells often a little larger than the leptodermous medullary cells. Rhizoids lacking on erect, leafy shoots, present in small groups on stolons. Leaves distichous, rather widely laterally spreading, the insertion transverse to weakly or distinctly incubous, canaliculate-conduplicate, boat-shaped but without a keel, the dorsal halves lying slightly more displaced toward shoot apex than the ventral, incubously imbricate, the leaf thus with an incubous appearance in dorsal aspect, the leaves unistratose throughout; apices undivided and entire to emarginate or bidentate, or 4-dentate, or (3)4-lobate; leaf margins entire or irregularly toothed. Cells leptodermous throughout, at most the cells above the base with slight, evenly thickened walls; cells in basal area becoming very large, more inflated, forming a distinct area basalis, the cells of all but the area basalis relatively small, subquadrate to oblong to polygonal; surface papillose, the surface of area basalis cells smooth or striolate or papillose. Oil-bodies totally lacking in both leaf and stem cells; oil-droplets present in some populations of Lembidium nutans, tiny, homogeneous. Underleaves conspicuous throughout, ca. 0.5 the width and 0.3 the area of the lateral leaves, the apices crenulate-denticulate to shallowly or deeply bilobed. Asexual reproduction absent, or (L. longifolium) via caducous leaf lobes.
Androecia (known only for Lembidium nutans) on short, apparently always ventral-intercalary branches from near the bases of erect, leafy stems or from stolons, short and spicate; bracts ovate, inflated; antheridia 1(2) per bract, the stalk rather short, uniseriate; bracteolar antheridia rare. Gynoecia on very short, apparently ventral- or lateral-intercalary branches, from ± fleshy, microphyllous shoot bases. Gynoecial bracts in 3 series, gradually larger, imbricate, those of innermost series lanceolate to narrowly ovate-lanceolate, tapered to a narrow, pointed or bidenticulate tip; upper margins and apex with ± crenulate margins by free ends of elongated cells, otherwise entire. Perianth exceedingly slender, trigonous, very long (ca. 7× longer than wide) and extremely attenuated, fusiform, the apex shallowly to obscurely lobulate and crenulate with narrow, often curved cells that are somewhat thick-walled and free at the rounded, finger-like tips (or occasionally a few cells wholly free), the cells distinctly papillose (although perianth below apex is smooth).
Sporophyte known only in Lembidium nutans. Seta formed of 8(9) rows of very large outer cells surrounding a core of numerous, much smaller cells. Capsule long-ellipsoidal, ranging from 350 × 1120 µm to 560 × 1400 µm, the wall (2)3-stratose; outer layer of cells with nodular (radial) thickenings of, generally, both faces of alternating longitudinal walls, the thickenings ± confluent to form continuous sheets; innermost layer of cells with semiannular bands, the bands usually complete.
Spores 12.5–14.4 µm in diam., dark yellowish brown, rather coarsely papillose, with short irregular papillae coalescing to form clumps or short ridges that rarely delimit areolae. Elaters rigid, ± straight, 8.6–11.5 µm wide, slightly tapering toward tips, bispiral to tips, the spirals 3.8–4.8 µm wide.
Key to Species
A genus with only two species, both found only in New Zealand.
References: Schuster and Engel (1987b; mon.); Schuster (2000a).
