Flora of New Zealand Series

[Plate 9B, E; Fig. 110: 2, oil-bodies, p. 486]

Plants ribbon-like, loosely creeping, pale green to pure green in dense shade, to 440 µm wide with rudimentary leaves (to 825 µm wide in var. flagelliformis). Branching common, pseudo-dichotomous, the branches of Frullania type, more vigorous and displacing the parent axis to one side, the branches often from only one side of axis; ventral-intercalary branches forming normal axes with rudimentary leaves, or hyaline, geotropic flagelliform axes, the geotropic axes with leaves reduced to solitary papilliform cells; apices of shoots at times becoming microphyllous and flagelliform. Axis dorsiventrally flattened, biconvex to less often planoconvex, formed of 2(3) rows of exceedingly large, polygonal to hexagonal cells (4–5 cells broad in var. flagelliformis), the lateral projections being rudimentary leaves; axis in ventral aspect with 6 cell rows, the 2 median rows (the ventral merophyte) somewhat narrower compared to the cells of the lateral merophytes (the ventral sectors of the lateral merophytes each 3–4 cells wide in var. flagelliformis); medulla composed of ca. 10–12 very narrow, strongly elongated cells, forming a small central strand. Rhizoids in fascicles from bases of the vestigial underleaves, the rhizoids with swollen, contorted and/or dendritic tips, the rhizoids forming a conspicuous haustorial disc in var. flagelliformis. Leaves reduced, separated by intervals formed by more than a full cortical cell, consisting of 2-celled, crescentic, lateral projections, each cell inflated and bearing at its apex a crescentic, hyaline, smooth papilla that is connate to the lobe cell along the outer bulge (the papilla on the proximal cell usually slightly larger, 85–90 µm long vs. 45–55 µm long for the papilla on the anterior cell), the leaves consisting of 3–4 cells in var. flagelliformis. Oil-bodies occupying tiny fraction of cell, very pale and somewhat grey, (6)8–9(11) per upper thallus cell, subglobose to elliptic to fusiform, coarsely papillose, 3.8–4.3 × 6.2–7.2 µm to 3.4–4.3 × 8.2–9.6 µm. Underleaves vestigial, consisting of 2, small, contiguous, inflated cells, each bearing an elongated, hyaline cell, which may bear a small, terminal hyaline papilla. Asexual reproduction absent. Fungal partner an ascomycete.

Androecia on ventral-intercalary branches; bracts leaf-like, bilobed, concave; antheridia 1 per bract, the stalk biseriate. Gynoecia on abbreviated ventral-intercalary branches from normal, ribbon-like shoots, or lateral- or ventral-intercalary from geotropic, flagelliform axes; bracts and bracteoles similar, those of innermost series bifid to 0.5–0.65(0.75), the lobes often narrow, terminating in a single cell or a uniseriate row of 2–4(6) cells, the margins often with a small lateral tooth. Perianth fusiform to obpyriform-fusiform, unistratose, the mouth deeply 6-lobed, the lobes narrow, (2)3–4 cells broad at base and with a few to several biseriate tiers, terminating in a uniseriate row of 5–6 moniliform cells.

Seta with 8(9) rows of outer cells surrounding an inner core of 10–16(19) rows of much smaller cells. Capsule broadly ellipsoidal, the wall 2-stratose; outer layer of cells with primary walls hyaline, each with 1 longitudinal secondary wall and sporadically a transverse wall, the secondary walls with brown nodular thickenings that are confluent, the walls appearing sinuous; inner layer of cells with weak, yellowish brown semiannular bands.

Spores 13–17 µm in diam., pale brown, delicately areolate. Elaters 8.5–10 µm wide, bispiral, the spirals 2.4–2.6 µm wide.

Comments : An extraordinary plant. The leaves are comprised of 2 projecting chlorophyllose basal cells, each at its summit with a sausage-shaped or crescentic, smooth, 1-celled papilla that is attached by its longer side. Zoopsis setulosa also has leaves formed by 2 projecting chlorophyllose basal cells, but in that species each of the 2 basal cells has a 2-celled appendix that is falcate or hooked and has a conspicuously roughened surface. Also, the appendix is attached by the narrow base of the basal cell.

Zoopsis argentea may be subdivided into two varieties, as follows.