Medium-sized to very large acaulescent herbs, seasonally dying back and dormant; stem a usually subglobose tuber. Leaf normally solitary subtended by several basal cataphylls; petiole erect, cylindric, not pulvinate apically, usually smooth, rarely verrucose (A. paeoniifolius), often conspicuously spotted; blade widely spreading, in outline forming a shallow inverted cone, tripartite, each major segment highly divided subpinnately or ± irregularly; ultimate lobes linear to broadly elliptic or ovate, with acuminate tips and broadly decurrent bases; venation of the ultimate lobes penniform, forming inframarginal veins on each side. Inflorescence normally produced before (more rarely with) appearance of leaves; peduncle normally shorter than petiole. Spathe usually with convolute basal portion forming cylindric to bowl-shaped tube, upper portion usually ± expanded, much broader, often with undulate margins. Spadix with basal pistillate portion contiguous with central staminate portion or separated by a short naked interstice, apical portion a variously shaped, sterile, ± smooth (rarely rugose or staminodial), terminal appendix, spongy fibrous within. Flowers unisexual, without perigon. Stamens usually densely congested, in groups of up to 6 (rarely more), sometimes connate basally; anthers usually sessile, more rarely with distinct filaments, dehiscing by apical pores (rarely by transverse slits); connective usually thick. Pistils usually densely congested, sometimes ± distant; ovary 1–4-locular; ovules 1 per locule on basal to axile placentas; style often elongated, sometimes lacking; stigma subglobose or variously lobed, often brightly coloured. Berries borne in ± cylindrical infructescence, 1–several-seeded. Seeds smooth, lacking endosperm.
HABIT : seasonally dormant (sometimes irregularly so) or rarely semi-evergreen herbs, often large, sometimes gigantic, tuber usually depressed-globose, sometimes irregularly ± elongate-cylindric, napiform or carrot-shaped, rarely rhizomatous or stoloniferous. LEAVES : usually solitary (rarely 2-3) in adult plants, sometimes 2-3 in seedlings. PETIOLE : long, usually smooth, rarely verrucose to asperate, sometimes very thick, usually conspicuously spotted and marked in a variety of patterns, sheath very short. BLADE : trisect, primary divisions pinnatisect, bipinnatisect or dichotomously further divided, tubercles rarely present at junction of divisions, secondary and tertiary divisions ± regularly pinnatifid to pinnatisect, ultimate lobes oblong-elliptic to linear, acuminate, decurrent, rarely petiolulate; primary lateral veins of ultimate lobes pinnate, forming distinct submarginal collective vein, higher order venation reticulate. INFLORESCENCE : always solitary, preceded by cataphylls, usually flowering without leaves, rarely with the leaves. PEDUNCLE : very short to long, similar to petiole. SPATHE : variously coloured, marcescent and finally deciduous, boat-shaped and not or hardly convolute, or clearly differentiated into tube and blade, sometimes constricted between them; tube convolute, rarely connate (A. pusillus, A. elliotii), campanulate to cylindric or ventricose, inner surface smooth, longitudinally ribbed, near base verruculose, scabrate or densely covered with scale- or hair-like processes or smooth; blade erect to spreading, smooth, ribbed or variously undulate or frilled at margins. SPADIX : shorter or much longer than spathe; female zone shorter, equalling or longer than male zone; male zone cylindric, ellipsoid, conoid or obconoid, usually contiguous with female, sometimes separated by a sterile zone which may be naked, or bear prismatic, subglobose or hair-like sterile flowers; terminal appendix usually present, rarely absent or reduced to stub, erect, sometimes horizontal, rarely pendent, very variable in shape, usually ± conoid or cylindric, rarely ± globose, sometimes ± stipitate or basally narrowed, usually smooth or bearing staminode-like structures near base or entirely covered with staminodes, sometimes corrugate or densely to sparsely hirsute, or grossly and irregularly crumpled. FLOWERS : unisexual, perigone absent. MALE FLOWER : 1-6-androus, stamens free or sometimes connate in basal flowers or throughout male zone, short, filaments absent or distinct, connective fairly thick, sometimes projecting beyond thecae, thecae obovoid or oblong, opposite, dehiscing apically by an apical (rarely lateral) pore or transverse slit. POLLEN : extruded in strands, inaperturate, mostly ellipsoid to ellipsoid-oblong, occasionally spherical or subsphaeroidal, medium-sized to large (mean 53 µm., range 34-82 µm.), exine striate, striate-reticulate, psilate, punctate-foveolate, verrucate, or spinose. FEMALE FLOWER : gynoecia usually crowded, sometimes ± distant, ovary subglobose to ovoid or obovoid, 1-4-locular, ovules 1 per locule, anatropous, funicle very short to distinct, erect, placenta axile to basal, style absent, short or very long, conoid to cylindric, stigma variably shaped, entire and subglobose or 2-4-lobed, stellate or rarely punctiform, sometimes large and brightly coloured. BERRY : sometimes very large, 1 to few-seeded, orange to red, rarely blue or white, infructescence ± cylindric. SEED : ellipsoid, testa smooth, thin, embryo large, somewhat green superficially, endosperm absent.
Seasonally dormant; petiole long, terete, variously spotted or patterned; leaf blade dracontioid, leaf solitary in each growth period; ultimate leaf lobes usually oblong-elliptic, acuminate, with primary lateral veins forming regular submarginal collective vein on each side. Differs from Pseudodracontium in having a 1-4 locular ovary, a terminal appendix which is smooth, rugose, or rarely verrucose or staminodial but not stipitate (Pseudodracontium always has a 1-locular ovary and a staminodial terminal appendix which is separated from the male zone by a naked axial region).