Appressed hemiepiphytic climbers or vines; juvenile plants terrestrial with elongate internodes and mostly ovate blades, greatly modified when climbing, sometimes tightly appressed to climbed surface (shingle leaves); preadult plants with shorter internodes, usually climbing or pendent, the result of branching or reversion to preadult phase from adult foliage; adult plants usually appressed climbers with short internodes, sometimes scandent; caudices often somewhat flattened on one side, densely rooting at the nodes, usually on the flattened surface only; roots usually slender; petioles amplexicaule, sheathed 1/6 to throughout; sheath persistent or deciduous; blades membranaceous to coriaceous, mostly ovate to oblong-elliptic, often oblique and inequilateral, entire or pinnatifid, frequently fenestrate in 1-4 series per side; midrib sunken above, raised below; primary lateral veins sunken above, prominently raised and whitish below; interprimary veins straight or branched especially toward the margins; tertiary veins distinct; INFLORESCENCES much shorter than the leaves, 1-several per axil; peduncle shorter or longer than the spathe; spathe deciduous, coriaceous, caviform, orbicular to naviculiform, usually white to pinkish or yellowish; spadix sessile, white to yellow, cylindroid, usually sterile at the base. Flowers densely aggregated in several spirals, perfect, naked, protogynous; stamens 4, extrorse, the pollen emerging in viscid threads; pistils oblong, prismatic, truncate at apex; style conical, the stigma linear, curved or straight. INFRUCTESCENCE green, white, yellow or orange, the stylar portion of the berries deciduous to expose the seeds; seeds globose to oblong, the raphe S-shaped by curvature of the seed in development; testa brown and soft, the embryo macropodial, green or blue. Species ca. 60,
HABIT : evergreen climbing herbs. LEAVES : distichous, juvenile leaves sometimes of shingle plant form, rarely variegated. PETIOLE : geniculate apically, sheath usually long, persistent or decomposing to fibrous or membranous mass or entirely deciduous. BLADE : entire, oblique, oblong to ovate-elliptic, often conspicuously and elaborately perforated, more rarely deeply pinnatifid; primary lateral veins pinnate, running into marginal vein, rarely forming an irregular submarginal collective vein (M. obliqua), secondary laterals often parallel-pinnate, sometimes reticulated (e.g. M. dubia), higher order venation reticulate. INFLORESCENCE : 1-several in each floral sympodium. PEDUNCLE : shorter than petiole. SPATHE : ovate or oblong-ovate, cuspidate, boat-shaped and somewhat convolute basally, white to rose-coloured within, remaining open after anthesis, caducous. SPADIX : sessile, subcylindric, somewhat shorter than spathe. FLOWERS : bisexual, perigone absent, lowermost flowers usually sterile. STAMENS : 4, filaments flattened, connective slender, thecae oblong-ellipsoid, dehiscing by longitudinal slit. POLLEN : fully zonate, hamburger-shaped, medium-sized (mean 48 µm, range 40-52 µm), exine densely foveolate to subreticulate, sparsely and shallowly foveolate or psilate, apertural exine verrucate or rugulate. STERILE FLOWERS : with 4 minute, conic staminodia, pistillode 2-locular, prismatic, lacking ovules. GYNOECIUM : obovoid to ellipsoid, prismatic, ovary 2-locular, ovules 2 per locule, anatropous, funicle short, placenta axile at base of septum; stylar region often massive, broader than ovary, apex truncate to shortly attenuate, stigma oblong-elliptic to linear (in the sense of the spadix axis). BERRY : 1-3-seeded, shedding prismatic stylar region at maturity, pulpy within. SEED : obovoid to ellipsoid, compressed, testa smooth, embryo large, endosperm absent.
Climbing hemiepiphytes with trichosclereids abundant in all tissues; petiole geniculate apically, sheath long, persistent to deciduous; leaves distichous; leaf blade with the two sides usually unequal, fine venation from parallel-pinnate to reticulate; spathe deciduous after flowering; flowers bisexual, perigone absent; ovaries 2-locular. Differs from from Stenospermation and Rhodospatha in more diverse leaf shape, usually perforated or pinnatifid or sometimes both, seeds globose to oblong, 6-22 mm long, endosperm absent and 2 ovules per locule.