Adelanthus falcatus (Hook.) Mitt.
Jungermannia falcata Hook., Musci Exot. 1: tab. 89. 1818, non J. falcata Raddi, Jungermanniogr. Etrusca 22. 1818 [≡ Diplophyllum albicans (L.) Dumort.].
Plagiochila falcata (Hook.) Gottsche, Lindenb. & Nees, Syn. Hepat. 649. 1847, non P. falcata Steph., Sp. Hepat. 2: 248. 1902.
Adelanthus falcatus (Hook.) Mitt., J. Proc. Linn. Soc., Bot. 7: 243. 1864.
Odontoschisma falcata (Hook.) Trevis., Mem. Reale Ist. Lombardo Sci. Lett. III, 4: 419. 1877.
Calyptrocolea falcata (Hook.) R.M.Schust., Rev. Bryol. Lichénol. 34: 689. 1967 (1966).
Type: New Zealand, South Is., Dusky Bay, 1791, Menzies (G!).
Plagiochila pusilla Mont., Ann. Sci. Nat. Bot. II, 19: 246. 1843.
Jungermannia pusilla (Mont.) Hook.f. & Taylor, London J. Bot. 3: 578. 1844, non J. pusilla L., Spec. Pl. ed. 1. 1136. 1753.
Type: Nova-Hollandia, Tasmania (= Van Diemen), sin. coll., “ex Herb. Mus. Paris, ex Montagne” (G!).
Plagiochila intermixta Colenso, Trans. & Proc. New Zealand Inst. 21: 49. 1889 (1888).
Type: New Zealand, Dannevirke, 1888, Colenso.
Plagiochila subpetiolata Colenso, Trans. & Proc. New Zealand Inst. 21: 49. 1889 (1888).
Type: New Zealand, Whakatane Co., near L. Waikare, 1887, Hamilton.
Marsupidium capillare Berggr., On New Zealand Hep. 36. f. 25. 1898.
Plagiochila capillaris (Berggr.) E.A.Hodgs., Trans. Roy. Soc. New Zealand 85: 581. 1958, non P. capillare Schiffn. in Steph., Sp. Hepat. 6: 137. 1918.
Adelanthus capillaris (Berggr.) E.A.Hodgs., Trans. Roy. Soc. New Zealand, Bot. 3: 77. 1965.
Type: New Zealand, South Is., Canterbury Prov., Castle Hill, Berggren 3156.
Plagiochila appressifolia Steph., Sp. Hepat. 6: 124. 1917.
Holotype: New Zealand, Mamaku, 600 m, “Ende April 1903,” Fleischer 65 (G!).
Plagiochila inaequalis Steph., Sp. Hepat. 6: 169. 1918.
Holotype: New Zealand, Mt. Winterslow, Beckett 484 (G!); isotype: (CHR 585839 ex herb. Beckett!).
Plants with erect leafy shoots arising from a copiously ramified system of leafless, rhizoidous axes, gradually smaller-leaved to leafless and freely ramified below, the leafy shoot tips smaller-leaved, tapered, strongly cernuous to circinate, the leaves pure green and nitid, the stems becoming black and opaque with maturity, the plants medium-sized, to 2.5 cm tall. Branching ventral-intercalary or from ventral bases of lateral leaves, rarely and sporadically the leafy shoot furcate, with a terminal, Frullania -type branch; intercalary branches also occasional from distal half of leafy shoots, the leafy shoot system (optimally) subdendritic; leafless axes interwoven, intricately branched; ventral branches, eventually leafy and phototropic, usually bearing a creeping or geotropic axis just above their point of origin. Stems typically stiff and wiry, smooth, the cortical cells in 2 layers, small, fuscous-walled, very thick-walled, their lumina very narrow or almost obliterated on lower parts of axes, the outer medullary cells often a little firm-walled, grading into a central medulla of thin-walled hyaline cells, but with ± thickened angles seen in cross section. Leaves ventrally secund (in lateral aspect of shoot half or more of leaf lying below the imaginary midline of stem), erect to suberect, vertical, the larger leaves imbricate as seen in lateral aspect, subtransversely oriented, strongly asymmetric, orbicular-ovate to subreniform-ovate, broader than long, the ventral portion distinctly ampliate, 1000–1200 µm wide × 850–900 µm long, to 1525–1550(1650) µm wide × 1125–1150 (1520) µm long, the leaves gradually becoming much smaller toward the circinate apices; margins broadly rounded above, with numerous unequal but small teeth separated by lunate sinuses (only rarely weakly toothed), the teeth extending to within 0.3 of leaf base but lacking from the dorsal margin, on larger leaves the teeth or serrations irregular, 40–50, broad-based, sometimes coarse and jagged; upper leaves smaller, obovate, often becoming longer than broad, almost symmetrical, with only 12–20 serrations. Cells firm-walled, lacking trigones and wall pigments, those in peripheral leaf sectors ranging from ± quadrate to obliquely quadrate or diamond-shaped, tending to lie in concentric arcs, forming longitudinal lines; marginal and submarginal cells 15–20 µm wide, thick-walled, gradually grading into the median cells; subapical cells 19–26 µm wide and long, the median cells with walls somewhat thinner than both subapical and marginal cells, the lumina more rounded at angles (vestigial trigones distinct), 15–21 µm wide × 20–35 µm long, varying from short-oblong to oblong-hexagonal or diamond-shaped; extreme base with an ill-defined region of elongated cells, above insertion 15–23 µm wide × 42–58 µm long (2.5–4.5:1), not forming a distinct area basalis, with sinuously thickened longitudinal walls; surface smooth. Oil-bodies dull opaque, pale smokey grey, with a milky appearance, 6–9 per median leaf cell, obscurely and indistinctly finely papillose, variable and often irregular in shape: globose to elliptic to sublinear to subcrescentic, some deltoid in profile, most 2.4–3.8 × 5.8–7.7 µm and a few 2.9 × 4.8 µm, globose ones 3.4 µm in diam. Underleaves lacking, the ventral merophytes 2–4 cells broad. Asexual reproduction not seen. Fungal partner an ascomycete.
Androecia on abbreviated branches from stolons or bases of erect, leafy branches, compactly spicate, very small, often clustered, often coiled, often somewhat dorsiventrally compressed; bracts in 4–6 pairs, strongly and deeply saccate, the dorsal base strongly involute, the apices remotely and irregularly denticulate by the variously projecting apical ends of marginal cells, the marginal cells elongated at right angles to margin; antheridia 1(2) per bract, the stalk long and coiled. Gynoecial branches often clustered, developing a cylindrical-ellipsoidal to dumbbell-shaped, fleshy, green, thick-walled perigynium, 2.6–2.8 mm long and 925–975 µm in diam., at base with scattered, reduced small bracts and bractlets; bracts orbicular-ovate, unlobed or 2–3-lobed, serrulate to spinose-ciliate, the innermost bracts reduced in size.
Seta massive, with numerous rows of outer cells. Capsule ellipsoidal, the wall 56–70 µm thick, of 4–6 layers; outer layer of cells quadrate to short-rectangular, the radial walls with broad, strongly developed, nodular to spine-like thickenings that tend to be best developed on alternating longitudinal walls, the thickenings sometimes on transverse walls; innermost layer of cells with semiannular (to sometimes annular) bands common, narrow, at times incomplete, sporadically forked.
Spores 13–15.4 µm in diam., red-brown, with dense, low but sharply defined, close papillae and short simple or sometimes furcate vermiculate markings. Elaters ± tortuous, short and stout, 7.7–9.6 µm wide, only 86–120 µm long, moderately tapering to tips, bispiral, the spirals 2.4–2.9 µm wide.
Distribution and Ecology : New Zealand: Campbell Island, Auckland Islands (Fineran, 1971), Stewart Island (100–475 m), South Island (120–1680 m), North Island (290–700 m); Australia: Tasmania, New South Wales. In New Zealand known from Fiordland, Otago, Canterbury (Hooker Valley, Arthur’s Pass, Cass), Westland, Western Nelson, Volcanic Plateau, Taranaki, Gisborne and Northland EPs.
Common in densely forested areas over a rather broad altitudinal range (0–1680 m), often under Nothofagus (N. solandri, N. menziesii) and Dacrydium cupressinum forests. In such forests, it often is a component of the bryophyte-rich vegetation of the forest floor, where it may be a characteristic and abundant species. It is often found on stream banks, on gravel, stones, or boulders, or in seepage near stony-bedded streams. It is also rather frequent on rotted logs. It is found with Breutelia elongata, Canalohypopterygium tamariscinum, Cryptochila grandiflora, Dicranoloma billardierei, D. robustum, Geocalyx caledonicus, Heteroscyphus cymbaliferus, H. sinuosus, Trichocolea mollissima, Tylimanthus saccatus and Wijkia extenuata.
Comments : A characteristic and easily recognized species, distinct in the contrast between black, smooth, wiry stems and nitid, clear green leaves with conspicuous dentition. Equally distinctive are the ventrally decurved, almost hamate or coiled branch apices, which have progressively smaller and narrower leaves.
Sexual branches are freely produced in this species. However, they arise so far down, hidden by distal portions of plants and by accumulated debris, that they may be easily overlooked.
