Herbertaceae Müll.Frib. ex Fulford & Hatcher
Plants subisophyllous to isophyllous, usually erect, at times pendulous, straw-colored to yellowish brown to deep brown to reddish brown; shoots medium to large and vigorous; plants with a weakly to strongly developed system of basal, prostrate, rhizomatous stolons from which arise upright leafy shoots, the leafy shoots, in turn, forming geotropic, stoloniform branches. Branching sparing, irregular, predominantly ventral-intercalary, less often lateral-intercalary; Frullania -like branches rare and sporadic. Stems with cortex weakly to strongly differentiated, thick-walled, typically smaller than the medullary cells. Rhizoids typically restricted to stolons, at underleaf bases and, at times, from underleaves (less often from leaves), the rhizoids also at times on basal sectors of upright leafy shoots but rarely in distal sectors. Leaves with insertion weakly incubous, often subtransversely oriented, often ventrally secund and often ± falcate, ± symmetric to rather asymmetric, short-bifid (Olgantha) or 2–3(4)-lobed to 0.4–0.8 or more, the lobes acute to lanceolate, entire; lamina margins entire or with a few teeth or short cilia at the base. Cells evenly thick-walled or with strongly nodulose, often confluent trigones; cells in median to basal sector often elongated, at times forming a vitta that extends to varying degrees distally; striate-papillose. Oil-bodies (fide Schuster, 2000a) usually 6–12 or more per cell, homogeneous (Herbertus) or finely botryoidal (Triandrophyllum). Underleaves transversely inserted, symmetrical, with shape and form much as in leaves. Asexual reproduction lacking or some species of Herbertus with fragmenting leaves (1 sp. with caducous leaves).
Dioecious. Androecia isophyllous, terminal on leading leafy shoots, becoming intercalary; bracts similar to leaves but pouched at base, with 2–4(6) antheridia; bracteoles like the bracts, with antheridia; antheridial stalk long, 2(4)-seriate. Gynoecia isophyllous, terminal on leading leafy shoots; bracts and bracteoles ensheathing the perianth, similar to one another and basically with shape and form like those of leaves and underleaves but often with more teeth. Perianth ovate to elliptic, deeply plicate, the mouth deeply divided into 6–9 lobes ± similar to those of the leaves.
Seta massive, of numerous cells. Capsule subspherical or spherical, the wall 4–9-layered; outer layer of cells with one-phase ontogeny, with nodular thickenings; inner layer with semiannular bands.
Spores papillose or granular-vermiculate or with truncated tubercles, ca. 2–2.5× the elaters in diam. Elaters 2(3)-spiral.
Three genera belong here. Two, Triandrophyllum and Herbertus, have representatives in the southern temperate region, while the third does not. Olgantha R.M.Schust. (Schuster, 1996c) has only O. eophylla R.M.Schust., a plant from the hyperparamo of Ecuador (4200–4300 m).
