Antheliaceae R.M.Schust.
Antheliaceae R.M.Schust., J. Hattori Bot. Lab. 26: 236. 1963.
Type: Anthelia (Dumort.) Dumort.
Plants isophyllous, julaceous, closely prostrate, slender and terete, greenish to bluish green to brownish, with age plants often secreting a water-repellent whitish substance and appearing bleached; shoots small to medium in size. Branching usually laxly pinnate, the branches normally of Frullania type; Acromastigum -type branches rare; ventral-intercalary branches rare, stoloniform. Stems comprised of a moderately well-defined hyaloderm of thin-walled cells that collapse with age and 1–2 subepidermal layers of thick-walled cells that grade into a leptodermous medulla, the stem cells similar in size but the subepidermal cells somewhat smaller. Rhizoids colorless, mostly from underleaf bases, some sporadically scattered over ventral surface of stem. Leaves suberect to erect, transversely inserted, unistratose or locally bistratose, concave, oblong, bifid to 0.5–0.7, the lobes narrowly acute, the lobe and lamina margins entire. Cells, aside from marginal sectors, rectangular, thin- to equally thick-walled, trigones lacking; surface smooth. Oil-bodies lacking. Underleaves identical to leaves in form, size and orientation. Asexual reproduction absent.
Dioecious or (in ours) paroecious. Androecia on leading shoots, becoming intercalary; bracts leaf-like but somewhat ventricose at the base and less deeply lobed; antheridia usually 1 per bract, the stalk biseriate; bracteoles lacking antheridia. Gynoecia terminal on leading shoots, with several progressively larger, closely imbricate bracts and bracteoles that are leaf- and underleaf-like, appressed to the perianth and form a compact bud-like, swollen, abruptly clavate capitulum; coelocaule-precursor distinct, low to rather high, the foot growing down into the shoot tip; shoot-calyptra present. Perianth distinct, ovate to oblong in outline, arising from a stout, swollen stem apex, pluriplicate, contracted at the mouth, often deeply 3–6-lobed.
Seta short, of the general type, with ca. 16–24 rows of outer cells surrounding numerous inner cell rows identical in diameter. Capsule spherical or nearly so, usually only shortly exserted, the wall 2-stratose; outer layer of cells usually subquadrate, never consistently elongated, not tiered, with one-phase ontogeny, all walls (except isolated short ones) with 1–2 strong nodular thickenings; inner layer of cells elongated, with semiannular bands mostly incomplete, occasionally complete, the radial walls also with nodular thickenings.
Spores delicately papillose, 1.5–2.5× elater diam. Elaters short, often tortuous, the ends weakly to strongly tapered, 2 broad or 3 narrow spirals.
