Lembidium longifolium R.M.Schust.
Lembidium longifolium R.M.Schust., Phytologia 45: 420. 1980.
Type: New Zealand, North Is., Little Barrier Is., Summit Track of Mt. Hauturu, SE of summit of Mt. Herekohu, 1700–1900 ft., Schuster 51446.
Plants dull-textured, light bluish green (in herb. the older portions fading to ivory-white or tawny), creeping; leafy shoots to 1.6 mm wide, strongly dorsiventrally compressed, densely leafy and pectinate-distichous, the shoot tips somewhat (often feebly) cernuous. Branching common, the leafy axes arise from, and give rise to, microphyllous to virtually leafless, rhizoid-bearing whitish stolons and flagella, the leafy axes simple or, more often, bearing 1–2(4) Frullania -type leafy axes arising only from one side of main axis. Branches of leafy shoots mostly of Frullania type, rarely more than 1–2 per leafy, erect axis, arising via an acute bifurcation but with leading axis retaining its dominance, the branch laterally displaced. Stems of leafy shoots soft-textured, somewhat fleshy; cortical cells large, thin-walled, hyaline (lateral cortical cells in surface view very large, in 2–3 tiers between each pair of leaves, in stem cross section in 15–16 rows, the dorsal moderately thick-walled, not differentiated in cross section from medullary cells; medullary cells rather leptodermous; surface of cortical cells smooth in sharp contrast to the strongly and closely papillose basal leaf cells. Leaves contiguous-imbricate in 2 sharply defined ranks, spreading at nearly right angles (but the apical sectors again arched forward), strongly elongated, to 650–725 µm long, or more, folded-canaliculate so that they cannot be artificially flattened, shaped somewhat like the lateral half of a canoe, basically narrowly ovate in outline, orientation almost vertical, but so oriented that the leaves are clearly incubous, the leaves in antical aspect clearly incubously inserted; apices convergent, loosely folded (U-shaped in cross section), consistently (3)4-lobed for 0.18–0.24 their length, the lobes tapered, long-acute; leaf margins sinuous and irregularly paucidentate, the teeth very variable, sharp and oblique and 1–3-celled to spreading or recurved, the short cilia formed of 1–2 elongated cells; antical leaf bases typically with 1–2 often arched or reflexed, 1–2-celled cilia. Cells thin- to very weakly and equally thick-walled, all strongly and closely to contiguously papillose, the papillae subspherical, readily detached, mostly high and rounded; cells of lamina, from apical lobes to antical and postical bases, rather uniform in size and shape, mostly subquadrate to polygonal, occasionally (usually locally and sporadically) moderately elongated, 15–21 µm wide × 20–28(45) µm long; laminar cells peripheral to base gradually grading into a small basal region of enlarged, but not inflated cells, the largest of which (in basal 1–3-celled tiers) range to 16–25(32) µm wide × 38–62(82) µm long; basal cells closely papillose like other leaf cells, but the papillae often rather elongated and lower. Underleaves narrower than stem, closely to loosely appressed, moderately concave, contiguous below to imbricate above, rather narrowly ovate, typically 0.25–0.35 bifid, sometimes with one, or less often both lobes reduced to 2–4-celled cilia, the lobes and/or cilia acuminate to long-acute; underleaf margins armed, like leaf margins, with irregular, chiefly 1–2-celled, often reflexed (especially near underleaf bases) teeth and short cilia. Asexual reproduction by caducous lobes of leaves. Otherwise unknown.
Distribution and Ecology : Endemic to New Zealand: South Island (40–80 m), North Island (400–750 m), Chatham Islands. Known from Westland, Western Nelson, Volcanic Plateau and Auckland EPs.
The species has a sporadic distribution, occurring from Haast Pass north to the northern sector of Westland and in the North Island from the Herangi Ra. (ca. 720–750 m) north to the Kaimai Ra. (400–425 m) and Coromandel Forest Park (510–540 m); also on Little Barrier Island (type). A characteristic niche is that of shaded vertical banks (usually associated with streams) and cliff faces. For example, it is associated with Paracromastigum furcifolium on the concave portion of the lip at the upper extreme of a deeply shaded vertical bank, the lip formed by the forest edge above. The station is in a stream valley under Beilschmiedia tawa and Weinmannia silvicola with a subcanopy of Schefflera digitata, Cyathea dealbata and C. smithii and a shrub layer of Freycinetia baueriana and Cortaderia (Kaimai Ra., headwaters of Poupou Stream). In the Herangi Ra. it formed large patches on a bryophyte-covered vertical, moist, south-facing cliff of ca. 5 m high (S of Te Whakapatiki, W of Te Kuiti). On Little Barrier Island occurring on a shaded, moist, very sheltered cliff face in the transition from Agathis australis forest to Beilschmiedia tawa – Weinmannia silvicola forest (520–580 m, type), admixed with Hymenophyllum ferrugineum. In the South Island it has been found under Weinmannia racemosa, Nothofagus solandri and N. truncata forests with associated species Balantiopsis convexiuscula, Hymenophyllum sanguinolentum, Hypnodendron arcuatum, the creeping vine Metrosideros diffusa, Mittenia plumula, Psiloclada clandestina, Saccogynidium australe, Sticta filix, Telaranea herzogii, T. tuberifera, Zoopsis leitgebiana and Z. setulosa.
Unlike Lembidium nutans, this species occurs only in exceedingly densely shaded sites, typically in deep, dark recesses or cave-like sheltered places, where humidity is high, but plants are sheltered from direct rain.
Comments : The dull, slightly bluish green color, the almost velvety texture and the very compressed shoots are diagnostic. Lembidium longifolium is strikingly different from L. nutans, chiefly in 1) the narrower leaves, with the shoots thus appearing more compressed; 2) the tendency for the leaves to be very conspicuously lobed at the apex and for the margins to bear several irregular, jagged teeth; 3) the leaf cells more nearly uniform throughout the leaf, without a prominent basal zone of conspicuously enlarged, inflated, smooth cells; 4) exceedingly closely papillose surface, with the rounded papillae easily detached when leaf cross sections are cut; and 5) underleaves always narrower than the stem, ovate from a broad and truncate base and usually clearly bilobed at the narrowed summit, the lobes and/or lateral flanks typically bearing 1–several conspicuous teeth or cilia. Leafy shoots are much more frequently branched than in L. nutans and the branches always are formed only along one side of the main axis, just as in Bazzania.
