HABIT : very small to medium-sized, seasonally dormant or evergreen, rarely pubescent (T. hirsutum) or glandular-pubescent herbs, tuber globose, subglobose or irregular, sometimes rhizomatous or stoloniferous, rarely an epigeal stem (T. fultum). LEAVES : few to several. PETIOLE : apex and middle portion rarely tuberculate, sheath rather short. BLADE : usually cordate-sagittate, sagittate to hastate, trifid, pedatifid or pedatisect, rarely linear, narrowly lanceolate, elliptic-oblong or cordate, apex rarely tuberculate; primary lateral veins of blade or lobes pinnate, forming submarginal collective vein, 1-2 marginal veins also present, higher order venation reticulate. INFLORESCENCE : solitary, appearing with or without (T. hayatae) or after the leaves. PEDUNCLE : shorter than petiole. SPATHE : constricted between tube and blade, tube with convolute or rarely basally connate (T. hirsutum) margins, persistent or rarely evanescent (T. nudibaccatum), blade eventually bending backwards from constriction, broadly ovate to lanceolate, ± acuminate, usually purple, rarely white within, tube persistent, blade marcescent. SPADIX : sessile, shorter, subequal to or much longer than spathe, female zone cylindric, subconic to subglobose, separated from male zone by rather long axis covered either entirely or only in basal part with sterile flowers of various shapes, rarely with sterile flowers above male flowers, male zone cylindric to ellipsoid, usually densely but rarely sparsely flowered (T. albispathum), appendix usually shortly stipitate, rarely with disc-like extension at the base or not stipitate at all (T. hirsutum), smooth, conoid to extremely slender, filiform-subulate, usually long-exserted. FLOWERS : unisexual, perigone absent. MALE FLOWER : 1-3-androus but usually 1-androus, sometimes 2-3-androus and ± connate, anthers subsessile, connective slender, sometimes prominulent, thecae ovoid to ellipsoid, dehiscing by pore or lateral slit extending to the middle or nearly to the base and confluent apically. STERILE FLOWERS : either all similar or diverse in the same spadix, capitate, clavate to spathulate, cylindric, filiform or subulate, rarely stout and flattened at the tip, or reduced to verrucae, straight to flexuose, suberect, spreading or decurved. POLLEN : extruded in amorphous mass, inaperturate, spherical to subspheroidal, medium-sized (mean 32 µm., range 28-36 µm.), exine spinose (spines very obtuse in e.g. T. trilobatum). FEMALE FLOWER : gynoecia oriented horizontally or vertically, ovary ovoid, ellipsoid or obovoid, 1-locular, ovules 1-3, orthotropous, funicle short, placenta basal, stigma sessile, discoid-hemispheric, facing upwards or sideways. BERRY : ovoid, 1- or rarely 2-seeded, orange-red, green or white. SEED : globose to obnapiform, testa thin, rugulose to smooth, strophiolate, embryo axile, elongate, straight, endosperm copious.
Very small to medium-sized seasonally dormant or evergreen geophytes; leaf blade linear-lanceolate to sagittate, hastate or pedatifid, fine venation reticulate; inflorescence appearing with leaves; spathe with constriction, tube sometimes with connate margins; spadix male and female zones widely separated by zone bearing sterile flowers and often partially naked; flowers unisexual, perigone absent; placentation basal.