HABIT : evergreen, rarely seasonally dormant, small to medium-sized herbs, rhizome creeping, subepigeal, rarely hypogeal, slender to thick, internodes very short, rarely long. LEAVES : several, rarely solitary. PETIOLE : geniculate apically (geniculum very long in N. bintuluensis), usually smooth, rarely sparsely aculeate, uniformly green, sheath very short. BLADE : cordate-sagittate to sagittate-trifid or subtriangular, posterior divisions usually longer than anterior, all three divisions often long-acuminate; basal ribs usually well-developed, primary lateral veins of both anterior and posterior divisions pinnate forming submarginal collective vein, higher order venation reticulate. INFLORESCENCE : solitary, usually flowering with leaves, rarely without (N. bintuluensis). PEDUNCLE : usually relatively slender, shorter or equalling petiole. SPATHE : ovate- to oblong-elliptic, fully expanded, reflexed at anthesis, not constricted, decurrent on peduncle, green, persistent or marcescent. SPADIX : short- to long-stipitate, cylindric, female zone contiguous with male, rarely with a few sterile flowers in between, male zone longer than female, fertile to apex. FLOWERS : unisexual, perigone absent. MALE FLOWER : 2-4-androus, stamens obpyramidal, filament thick, well developed (except N. hallaei, N. mayombensis), connective thick, thecae lateral, anterior dehiscing by apical pore. POLLEN : presented in amorphous mass, inaperturate, ellipsoid to subsphaeroidal, medium-sized (mean 46 µm.), exine verrucate. FEMALE FLOWER : ovary ovoid, 1-locular, ovule 1, anatropous, funicle very short, placenta basal, stylar region shortly attenuate or inconspicuous, stigma discoid-hemispheric. BERRY : large, subglobose to ellipsoid, orange, pericarp thick. SEED : obovoid or subglobose to ellipsoid, smooth, testa absent at maturity, embryo large, outer cell layers with chlorophyll, endosperm absent.
Evergreen to seasonally dormant geophytes with creeping rhizome; leaf blade with reticulate fine venation; flowers unisexual, perigone absent. Differs from Callopsis in leaf blade cordate-sagittate or subtriangular, deeply sagittate or trifid, glabrous, spathe green, spadix entirely free of spathe. Differs from Stylochaeton in free spathe margins and absence of perigone. Differs from Cercestis in lacking pellucid gland lines or points in leaf blade and presence of submarginal collective vein, at least in upper part of leaf.