Fertile plants of M. capensis can be distinguished quite readily from other members of the Marchantiales by the stalked, domed and unlobed carpocephala, lacking a pseudoperi-anth. Sterile specimens are more difficult to distinguish, particularly from Targionia hypo-phylla and small Asterella plants. In T. hypo-phylla, however, the dorsal air pores are larger, and, when dry, white-encircled; in Asterella species, with the exception of A. muscicola, the air pores and air chambers are generally difficult to detect from above, fresh or dry.
Thalli smallish to medium-sized, in crowded patches; bright green, sometimes laterally reddish or bronzed, firm, compact, faintly areolate, air pores numerous, small, margins with narrow black borders distally, gradually widening prox-imally, somewhat scalloped; when dry, thallus margins tightly incurved and branches almost tubular. Branches simple or once, rarely twice, pseudodichotomously furcate, sometimes with apical or ventrolateral innovations, linear or strap-shaped, up to 12 mm long, 2-4 mm wide, 525-775 µm thick medianly, in section 4 or 5 times wider than thick, apex entire, tips of ventral scales reflexed over edge; groove absent, thallus flat to slightly concave dorsally, margins acute, quite thin; flanks sloping obliquely; ventral face medianly broadly keeled, black. Scales in 2 ventral rows, obliquely triangular or semi-lunate, black to reddish black, body ± 600 µm long, margins sometimes with few mucilage papillae, base concave, ± 600 µm wide, narrowed above without constriction to 1 or 2(3) linear-lanceolate appendages, up to 110 µm long, ± 17 µm wide at base, tapering to acute apex, oil cells scattered throughout. Dorsal epidermal cells unistratose, hyaline, trigones conspicuous but not bulging, externally covered with minute spicules, polygonal, 27-30 x 15-25 µm; air pores slightly raised, simple, ± 25 x 15 µm, surrounded by innermost ring of 7 small, collapsed cells, then by 2 concentric rings of 7(8) larger cells in each, radial walls not thickened. Assimilation tissue 200-250 µm thick, air chambers'in several storeys, densely crowded and incompletely bounded by unistratose walls, difficult to distinguish between bounding cells and those forming chlorophyllose filaments; storage tissue well developed, cells angular; oil cells scattered throughout tissues. Dioicous, rarely monoicous, but gametangia generally on different branches. Androecia with 2 to 4 rows of sunken antheridia along centre of branches, opening into conical papillae. Gynoecial receptacles terminal when young, sessile, knob-like, in V-shaped, apical sinus, surrounded by numerous, arched, dark purple lanceolate paleae, up to 1150 µm long, 4-6 cells wide at base, narrowing to one cell wide at apex, at maturity raised on stalk; carpocephalum ± 2 mm across, straw-coloured, domed to low conical, papillose centrally with compound pores, not or scarcely lobed below, bearing (1)2-4 capsules. Stalk 5-25 mm long, cylindrical, 400 µm wide, with single rhizoid furrow, only a few paleae carried along and also present at summit, but obscured. Involucres membranous, wide-mouthed and bell-shaped, each with single capsule. Sporophyte with short seta, capsules protruding, globose, dark brown, wall lacking annular thickenings, dehiscing by well-formed lid along row of smaller cells. Spores 75-80 µm diam., polar, roughly triangular-globular, light brown, semitransparent; wing lighter, straw-coloured, 7.5 µm wide, porate at each of 3 angles (or in between as well), wavy and undulating, inflated and twisted in side view; distal face convex, bearing 10-13 crowded and very conspicuous, hemispherical bullae, ± 22 µm wide, mostly well separated from each other, occasionally 1 or 2 collapsed, proximal face with raised base, triradiate mark present but weak, slightly raised or not, arms not extending to edge, with shallow, crowded and overlying alveoli in centre, both faces generally covered with granules. Elaters reddish brown, tapering toward ends, 212-275 µm long, 12.5 µm wide in centre, 7.5 µm wide at tips, bi- or trispiral.