Flora of New Zealand Series

Diplophyllum gemmiparum J.J.Engel & Merrill, J. Hattori Bot. Lab. 84: 255. f. 3. 1998. 

Holotype: New Zealand, South Is., Canterbury Prov., Arthur’s Pass Natl. Park, area immediately below summit of Avalanche Peak, Scotts Track, W of town of Arthur’s Pass, 1650 m, Engel 22042 (F).

[Fig. 165]

Plants loosely creeping to ascending, clear light green to deep red, but stems dark brownish in older sectors of plant, the ♂ bracts at least faintly reddish tinged, and clusters of gemmae at stem apices reddish orange; basal portion of plants repeatedly branched and soon becoming leafless; shoots small, to 1.8 mm wide. Branching common but irregular, lateral-intercalary, often with numerous subgynoecial innovations. Rhizoids common except near shoot tips, in distinct fascicles (or at least localized) from cortical cells just above the ventral leaf bases, but tending to become somewhat scattered in older portions of shoot. Stems flexuous, with differentiated cortex of 2–3 layers of thick-walled cortical cells; medullary cells thin-walled, colorless; ventral side of stem blackish, infected with dark-pigmented endophytic fungal hyphae. Leaves rigid, dorsally assurgent (particularly when dry), densely imbricate, bilobed, conduplicate-channeled, the basal portion loosely sheathing the stem, the keel 0.55–0.6 the length of leaf, obliquely spreading, rounded in section and not sharp, ± straight to weakly arched, the sinus broadly acute and not reflexed; dorsal and ventral lobes subequal in size but the dorsal always smaller, the ventral lobe plane to weakly reflexed, the dorsal erect to broadly squarrose-reflexed at the tip; lobes truncate and abbreviated in gemmae-producing leaves; leaf insertion ± transverse, the leaf bases overlapping dorsally, extending to more than half the width of the stem, the ventral bases overlapping, particularly in distal portion of shoot. Ventral lobe weakly channeled, typically only moderately reflexed, the margin not decurrent, the ventral half of leaf narrowly to broadly elliptic, at times subfalcate; apex rounded to broadly acute (rarely minutely apiculate), the apices of gemma-producing leaves becoming narrowed, broken and irregular, often with a broad, hyaline, caducous mucro, sometimes with occasional gemmiferous filaments persisting at the apex; ventral margin broadly arched, tapering to the base, the margins distinctly and somewhat irregularly toothed, the teeth somewhat larger near the base; dorsal margin toothed or at times subentire. Dorsal lobe erect to distinctly reflexed, similar to the ventral in shape but somewhat smaller, the insertion transverse, the dorsal half of leaf elliptic, 0.75–0.95 the length of ventral lobe, 0.65–0.9× area of the ventral; apex broadly acute to rounded, similar to that of ventral lobe; dorsal (free) margin broadly arched, contracted to the base, the teeth similar to those of the ventral lobe. Marginal teeth unicellular (at times with a transverse wall near the base), tapering, rounded at the tip, typically oriented ± at right angles to margin, straight to somewhat curved or hooked. Cells of median portion of ventral lobe short-rectangular, 11–14 µm wide × 14–21 µm long; distal portion of lobe densely areolate, the cells small, moderately thick-walled, the lumen distinctly rounded-elliptic to somewhat angular, the apical and submarginal cells smaller, irregularly arranged to aligned in transverse arching tiers, 7.5–9 µm wide × 8–10 µm long; median cells in basal undivided portion of leaf elongate-rectangular, in a broad band on both sides of leaf midline, forming a broad vitta, the cell walls evenly and only moderately thickened (the longitudinal walls rarely feebly sinuous), the vitta typically not extending distally beyond the keel, the cells of vitta 10–13 µm wide × 28–54 µm long (3–5:1); surface very coarsely papillose in distal portion of leaf, the papillae rounded to short-elliptic, 1–3 per cell in submarginal cells of lobes, often with a single papilla equaling or at times exceeding the cell lumen in diameter; elongate cells of median base striolate-papillose. Gemmae aggregated in dorsiventrally flattened buds at the tips of main shoot and branches, the gemmae produced in chains at the tips of uniseriate filaments clustered at the apices of young developing leaves, the production of gemmae often continuing as the leaves mature; gemmae brownish orange, 1-celled, angular to distinctly stellate, 11.5–12.5 µm diam., including papillae.

Paroecious, the ♂ bracts immediately below the ♀. Androecia with 3–4 pairs of ♂ bracts, the bracts ventricose, distinctly pouched, sometimes faintly reddish tinged at extreme base, the margin of dorsal lobe abruptly reflexed at apex; antheridia 2 per bract, the stalk elongate, uniseriate, the basal 2–3 tiers thick-walled. Gynoecia subtended by a pair of leaf-like bracts, the bracts larger than leaves, subequally lobed, erect and sheathing the perianth, sometimes with a smaller unlobed bract adjacent to the perianth. Perianth elliptic, plicate at least in distal 0.5, at times almost to the base, contracted at the mouth, shallowly lobulate distally, the lobule margins with sharply tapering, 1-celled teeth and denticulations formed by projecting ends of marginal cells; cells in region of mouth subquadrate to short-rectangular, moderately thick-walled, those of perianth proper thick-walled and with a rounded lumen.

Sporophyte not seen.

Distribution and Ecology : Endemic to New Zealand: South Island (1360–1650 m), North Island (2025 m). Known from Canterbury, Westland and Volcanic Plateau EPs, only from three high-alpine sites. The type collection came from deep in a shaded, protected niche between boulders of a rocky outcrop, intermixed with Diplophyllum dioicum, Hepatostolonophora rotata and Riccardia sp. on Avalanche Peak (Arthur’s Pass, 1650 m). At Rainbow Skifield (St. Arnaud Ra., Nelson Lakes Natl. Park, 1360–1480 m) in a mosaic of tussock grass and alpine vegetation along with tarns, rills, rocky outcrops and boulderfields, the species forms ± pure, thick patches where thick soil accumulated over an outcrop. In the North Island known only from cliffs and outcrops at 2025 m on the north slope of Mt. Ruapehu, an area characterized by periodic (as recent as 1995) volcanic activity. The ground surface consists of rock, gravel and volcanic cinder. The only vegetation observed in this rigorous habitat were a few bryophytes (confined to cliff and outcrop crevices) and a few scattered high-alpine flowering plants.

Comments : Gemmae of this species are distinctive, stellate-angular, orangish and are produced in terminal buds at the tips of the main shoot and branches (Fig. 165: 1, 8). The gemmae develop in chains on uniseriate filaments issuing from the apices of young developing leaves, although gemmae production often continues on older leaves farther down the shoot; these older leaves will occasionally retain one or more filaments along the margin. Older gemmae-producing leaves typically have the apex contracted to a broad, hyaline mucro, the cells of which are short-rectangular and smooth (Fig. 165: 7). This mucro subsequently breaks off, leaving the leaf with a truncate apex.

Perhaps the most remarkable feature of this species, apart from the abundant production of gemmae (Fig. 165: 1), is the aggregation of rhizoids in discrete bundles adjacent to the ventral bases of the leaves (Fig. 165: 2). This character also occurs in Blepharidophyllum and Clandarium of the Blepharidophyllaceae (see Grolle, 1965f), but terminal, Frullania -type branching is lacking, the lobe apices of Diplophyllum gemmiparum are not bifid and the leaves have a vitta strikingly similar to that of a number of other Diplophyllum species. In older portions of the stem, additional rhizoids often develop from other cortical cells, so that the localized arrangement of the rhizoids is obscured.