Flora of New Zealand Series

Cesia stricta Berggr., On New Zealand Hepat. 2. f. 2. 1898.

Acolea stricta (Berggr.) Steph., Sp. Hepat. 2: 7. 1901.

Gymnomitrion strictum (Berggr.) R.M.Schust., J. Hattori Bot. Lab. 26: 280. 1963. 

Type: New Zealand, North Is., Mt. Ruapehu, 1500 m, Jan. 1875, Berggren.

[Fig. 175: 4, oil-bodies, p. 787]

Plants laxly caespitose to procumbent, locally pale yellowish brown to fulvous brown (the leaf lobes and disc margins decolorate), weakly nitid when dry, the shoots very densely leaved, subterete to somewhat dorsiventrally flattened (then strongly convex ventrally, almost flat dorsally), to 475 µm wide. Branching sparing to irregular ( var. strictum) to copious and often clustered ( var. inaequalis), always lateral-intercalary; geotropic stolons usually few or rare. Stems almost colorless, pellucid, the cortex poorly differentiated, the cortical and medullary cells similar in diameter, both somewhat firm-walled, the exposed walls of the cortical cells at times thicker, at times bulging. Rhizoids few or rare, tending to be in small groups from near ventral leaf bases. Leaves erect-appressed, at times slightly dorsally assurgent, markedly densely imbricate, the stem nowhere visible, the median and basal sectors strongly concave, the hyaline margins and lobes nearly flat and appressed to anterior leaf; leaves narrowly to rather broadly ovate and 320–400 µm wide × 350–560 µm long to 400–420 µm wide × 600–625 µm long, bilobed to 0.15–0.25; lobes ± parallel, acute, often apiculate, terminating in a single, isodiametric to often slightly elongated cell, the lobe margins plane and not recurved, entire or crenulate by bulging walls of marginal row of cells; sinus acute to rectangulate, V-shaped, at times the sides flaring. Cells in lobe tips and margins thick-walled, lumina usually guttulate, the cells small, 10–17 µm wide × 11–20 µm long, mostly somewhat elongated parallel to margins in the lobes, less elongated on margins below the lobes; cells within lobes remaining guttulate ( var. inaequalis) or developing coarse, if ill-defined, trigones, the cells in lamina middle 11–20 × 17–26 µm, those near the base distinctly larger and 15–21 µm wide × (20)25–35(40) µm long; surface faintly to moderately asperulate. Oil-bodies occupying small volume of cell, hyaline, 2–4(5) per cell, coarsely granular, irregularly elliptic to irregularly linear, less often subglobose, 2.4–3.4 × 5.8–7.2 µm to 4.3 × 5.3 µm, a few long-linear and 2.4 × 7.7 µm, subspherical ones 3.4 µm in diam. Chloroplasts exceptionally large for cell size. Underleaves lacking.

Autoecious. Androecia a little broader than sterile leafy sectors, usually (always?) on lateral-intercalary branches, at times arising almost juxtaposed to the ♀ branches; bracts in many pairs (8–16 or more), densely imbricate, leaf-like, the lobes sometimes a little more crenulate with projecting cells, the base moderately ventricose; antheridia 1–2 per bract, the stalk 2-seriate. Gynoecia (always?) on lateral-intercalary branches, initially microphyllous and slender, usually soon leafy and, after 8–20 gyres, gynoecial, the gynoecium swollen and clavate, with bracts progressively much larger, erect-appressed, but dorsal margins often a little reflexed; innermost bracts large, free dorsally, otherwise connate to 0.5 or more into a strongly plicate sheath with ca. 5–6 major lobes (2–3 per bract, 1 representing the bracteole?, the intervening sinuses descending to 0.3), each lobe long-acute ( var. strictum) ranging to long-acuminate or piliferous ( var. inaequalis) and with margins crenulate to dentate; accessory, reduced bractlets often present within the connate innermost bracts, small, variable, sometimes lanceolate, 0.35–0.45 the length of the bracts. Perianth completely lacking. Calyptra with sterile archegonia at base.

Seta seen only in collapsed state. Capsule wall 2-stratose, 22–26 µm thick, the outer layer of cells with one-phase development, the longitudinal walls typically bearing very strong, ± coalescent, nodular thickenings lending a sinuous appearance, the transverse walls lacking thickenings or sporadically with a solitary thickening; inner layer of cells mostly less regular, with weak or small, widely separated nodular thickenings on all but the shortest walls, the thickenings moderately to distinctly smaller than those of the outer wall.

Spores pale reddish brown, 16.3–18.2 µm in diam., distinctly areolate, the ridges rather thick. Elaters not seen.

Distribution and Ecology : Endemic to New Zealand: Campbell Island (450 m), South Island (1040–2130 m), North Island (1200–1700 m). Known from Fiordland, Westland, Otago, Canterbury, Marlborough (Seaward and Inland Kaikoura ranges) and Volcanic Plateau EPs.

Occurring in the penalpine and alpine zones in rock crevices, on boulder faces, as well as in niches between boulders or, in Central Otago, on the schist tors. At times in shaded, more protected sites such as on the undersides of dripping ledges or deep under protective overhangs. In the penalpine zone occurring, for example, on a boulder face in an exposed stream valley through scrub of Halocarpus bidwillii, Ozothamnus leptophyllus and Phyllocladus alpinus (Taranaki Falls track, Tongariro Natl. Park, 1240 m). It has been found with Andreaea acutifolia, A. mutabilis, Andrewsianthus cuspidatus, Bartramia papillata, Conostomum pentastichum, Cryptochila grandiflora, Diplophyllum domesticum, Ditrichum punctulatum, Herbertus oldfieldianus, Herzogobryum teres, Hymenophyllum armstrongii, Notholigotrichum australe, Nothogymnomitrion erosum, Rhacocarpus purpurascens and Siphula rubra.

Comments : Plants of this species occasionally are completely bleached and then have the appearance of Anthelia, a plant with rather similar leaf shape and areolation. The absence of underleaves and the larger plant size will immediately distinguish such plants as Gymnomitrion. For other comments see under G. cuspidatum.

Two varieties have been recognized as follows; these require evaluation based upon the study of more material.