Laticifers present, simple, articulated. HABIT : seasonally dormant, aquatic herbs, continuation shoot of stem sympodium arising in axil of last foliage leaf of each article and beginning with a foliage leaf rather than a cataphyll, rhizome short, erect, buried deep in soil. LEAVES : several. PETIOLE : terete, sheath long. BLADE : oblong-elliptic, held above water surface or floating on it; primary lateral veins arising at base of blade, arcuately ascending and running into apex, secondary laterals inconspicuous and parallel to primaries, higher order venation transverse-reticulate. INFLORESCENCE : 1-2 in each floral sympodium. PEDUNCLE : absent, spadix supported on elongated stipe. SPATHE : a short, inconspicuous, simple bract, inserted at point of attachment of inflorescence to rhizome, enclosing young spadix, later separated from it and disintegrating. SPADIX : held above water level, conical, slender, flowering acropetally, golden yellow, peduncle-like stipe very long, often partly submerged, greenish to red-brown with white, swollen apical part. FLOWERS : bisexual except for some male flowers at spadix apex, perigoniate, tepals 6, sometimes 4, short, about as long as wide, fornicate, subtruncate, irregularly imbricate. STAMENS : 6, sometimes 4, filaments flattened, connective slender, thecae ellipsoid, dehiscing by broad apical slit. POLLEN : monosulcate, ellipsoid, large (mean 64 µm., range 55-73 µm.), exine densely foveolate-fossulate. GYNOECIUM : ovary depressed-globose, broader than long, 1-locular, ovule 1, hemianatropous, held horizontally, funicle short, placenta basal, style ± absent, stigma small, subsessile, discoid-hemispheric. BERRY : depressed-globose, green, 1-seeded, partially immersed in spadix axis. SEED : ± globose, testa thin, smooth, ± transparent, decaying at maturity, raphe conspicuous in furrow-like depression, hilum reddish, embryo large, almost globose to depressed-globose, with a small internal cavity situated below the hilum, outer cell layers green, plumule well-developed with 1(-2) filiform leaf primordia, endosperm absent.