HABIT : large herb with thick, hypogeal rhizome. LEAVES : numerous. PETIOLE : thick, flattened to deeply sulcate, sheath long. BLADE : becoming large, ovate-elliptic to ovate-oblong; primary lateral veins pinnate, running into inconspicuous marginal vein, higher order venation ± regularly transverse-reticulate between primaries. INFLORESCENCE : solitary, appearing just before or with the leaves in early spring. PEDUNCLE : absent, spadix supported on elongated stipe. SPATHE : marcescent, inserted at the point of attachment of spadix stipe to rhizome, cucullate to boat-shaped, lower part narrowly convolute and clasping spadix stipe, blade expanded, ovate, white or yellow. SPADIX : subcylindric, subacute at apex, stipe extremely elongated. FLOWERS : bisexual, perigoniate; tepals 4, cucullate, imbricate. STAMENS : 4, filaments oblong, flattened, connective slender, thecae ellipsoid, dehiscing by longitudinal slit. POLLEN : monosulcate, ellipsoid, medium-sized (mean 40 µm., range 38-43 µm.), exine reticulate. GYNOECIUM : elongate-ovoid, attenuate apically, ovary immersed in spadix axis, 2-locular or incompletely 2-locular, ovules 1-2 per locule, orthotropous, broad, conoid, funicle very short and thick, placenta axile, thick, style attenuate, longer than tepals, stigma discoid-hemispheric. BERRY : ellipsoid, mostly 2-seeded, green, decaying or stylar portion breaking off with perigone at maturity to expose seeds embedded in spadix axis. SEED : ± ellipsoid, somewhat compressed, testa smooth, embryo large, ellipsoid, endosperm nearly absent, present only as a single cell layer.
Temperate helophytes with thick, hypogeal rhizome; leaf blade entire, ovate to oblong, fine venation reticulate; spathe blade white or yellow; spadix stipe very long, enclosed by lower part of spathe for most of its length down to attachment with rhizome; flowers bisexual, perigoniate, tepals free; ovary 2-locular, ovules 2 per locule, orthotropous, placenta axile.