Plants medium to large, main shoots ca. 900–1600 µm wide). Initial branching appendages of the Incumbens-type, the ventral segment of the BUL1 to 250 µm long. Main leaflobes ±contiguous to slightly sub-remote on main stems, to 700 µm long × 500 µm wide, with strongly incurved distal margins, when flat with widely rounded to nearly subtruncate apices, base cordate, usually both dorsal and ventral bases auriculate-appendiculate. Lobules of the main stem typically subparallel to the stem or less commonly incumbent with apices strongly inclined toward the stem, lobuli typically distant or remote, occasionally contiguous or slightly imbricate, ca. 1.5–2Χ long as wide, to 350 (450) µm long × 225 (300) µm wide; the lobules campanulate, curved to subparallel sides with wide rounded apices, slightly constricted above the mouth; lobules of lateral branches typically strongly incumbent, dense and partially imbricate to each other, and slightly more elongated, often 2–2.25X long as wide. Underleaves of leading stems to 400 µm long × 325 µm wide, cuneate narrowed towards the base, narrow, transverse insertion, broadest in distal third where lateral margins are usually obtusely dentate or bluntly angular; underleaf 0.25–0.5 bilobed by a narrow slit to U-shaped sinus.
Lobemedian cellswith large subtriangular to slightly convex trigones, typically with semi-straight walls, often with nodulose intermediate thickenings present or lacking, both the trigones and intermediate thickenings (if present) hyaline with a thick red-brown pigmented secondary wall layer, the cells to 25 (35) µm long × 20 (25) µm wide, the cells becoming gradually larger basally; lobe basal group of cells with large bulging trigones and thin intervening walls, and rarely with nodulose intermediate thickenings. Underleaf and lobule median cells with weak sinuous walls. Asexual reproductionnone known. Oil-bodies of the lobe median cells (2) 3–6 (7) per cell, collectively occupying ca. 0.25–0.4 of cell lumen, subhyaline, surface appearing coarsely granular, the segmentation ± distinct, spherical, 3–4.5 µm in diam., to ovoid or ellipsoidal, to 8 µm long × 5 µm wide; of basal cells 5–7 per cell, becoming increasingly more botryoidal, and slightly larger.
Gynoecia terminal on main stem or leading branches, ♀ Bracts and bracteoles in 2–4 pairs, grading to subfloral leaves; innermost bract unequally bilobed, lobe oblong to ovate with acute to narrowly rounded apices, lobe margin entire; lobule almost equal in length to lobe (but narrower), ca. 0.3 connate, lanceolate to falcate, acuminate at apex, ventral margins with 1–2 strong teeth near middle. Innermost bracteole free or connate with female bract on one side, 0.3 to 0.7 bilobed, lobes triangular-lanceolate, acuminate-subulate apex, laciniate at base. Perianth exserted, large, to 1800 µm long × 800 µm wide, obovate-obpyriform, 2 broad lateral keels + 1 broad ventral keel, and occasionally inconspicuous, accessory keels, or becoming plicate towards the perianth apex and becoming retuse;surface smooth toward the very base and often the dorsal face, otherwise sparsely distributed with multicellular tubercles or subtriangular, scalelike outgrowths of (2) 3–5 (8) cells, particularly over the ventral surface and the keels; perianth beak cylindrical from base to apex, often long (ca. 1/8th in length of perianth) to 150 µm long.
Affinities, differentiation & variation:
Frullania anomala is the only species in subg. Australes with tubercles or scalelike outgrowths on the perianth surface, which are typically sparsely distributed over the entire ventral surface, particularly the ventral and lateral keels, and less often over the dorsal surface where they may be absent entirely. Hodgson (1949) astutely observed that this taxon appeared “nearest to F. incumbens, of which it might possibly be a parallel rough-perianthed form”. Indeed, in the absence of perianths this species is often difficult to distinguish from some forms of F. incumbens.
In gross morphology (excluding the perianth), only the lobules of the lateral branches tend to be strongly incumbent for F. anomala, whereas in typical forms of F. incumbens, the lobules of both the main stem and lateral branches have apices strongly inclined toward the stem. However, typical phases of both species can also be distinguished from each other by differences in the cell wall anatomy of the leaf-lobe: F. anomala has large subtriangular, convex trigones with semi-straight walls, occasionally lacking intermediate thickening, whereas F. incumbens has sinuose cell wall thickenings, including nodulose thickenings at the cell angles and nodulose intermediate thickenings. There also appears to be minor, but seemingly consistent differentiation on the basis of the number of oil-bodies in the basal cells of the leaf lobes.
Geographic distribution & ecology: Distributed throughout New Zealand, south of Auckland, and apparently a species associated with cool, wet conditions; in the North Island common above 800 m., and just below subalpine zones, but occurring at lower elevations southwards.