MORPHOLOGY

LEAF STRUCTURE

• Leaves usually solitary (rarely 2–3 together); petiole long, usually smooth, rarely verrucose to rough, sometimes very thick, usually conspicuously spotted and marked in a variety of patterns, rarely plain green; sheath very short.

• Leaf blade decompound, trisect, primary divisions usually pinnatisect, bipinnatisect, or dichotomously further divided, rarely undivided.

• Highest order divisions (leaflets) entire, never fenestrate or lobed, with one tip, oblong-elliptic to linear, acuminate, decurrent, rarely petiolulate.

• Tubercles rarely present at junction of divisions.

• Primary lateral veins of ultimate lobes pinnate, forming a distinct submarginal collective vein; higher order venation reticulate.

GROWTH HABIT

• Seasonally dormant (sometimes irregularly so) or, rarely, semi-evergreen herbs, often large, sometimes gigantic.

• Stem usually a depressed-globose tuber, sometimes irregularly ± elongate-cylindrical, napiform, or carrot-shaped, rarely rhizomatous or stoloniferous.

INFLORESCENCE

• Inflorescence usually solitary, rarely several together, subtended by conspicuous cataphylls.

• Plants usually flowering without leaves, rarely with leaves.

• Peduncle very short to long, often partially or ± hypogeal, generally similar to the petiole.

• Spathe variously coloured, marcescent and finally deciduous, boat-shaped, and not or hardly convolute, or clearly differentiated into lower tube and limb, sometimes constricted between them.

• Tube convolute, rarely connate, campanulate to cylindrical or ventricose, inner surface smooth, longitudinally ribbed, or variously verruculose, scabrate, or densely covered with scale- or hair-like processes.

• Spathe limb erect to spreading, smooth, ribbed, or variously undulate or frilled at margins.

• Spadix sessile or stipitate, shorter or much longer than spathe.

• Flowers unisexual, perigone absent.

  • Staminate flower zone cylindrical, ellipsoid, conoid, or obconoid; contiguous or separated by a sterile interstice bearing sterile flowers.

  • Staminate flowers 1–6-androus; stamens free or connate in synandria, thecae dehiscing by apical pores or transverse slits.

  • Pistillate flower zone shorter, equal, or longer than staminate zone; gynoecium subglobose to ovoid, 1–4-locular; stigma variably shaped and sometimes brightly coloured.

  • Appendix usually present, rarely absent, very variable in shape and texture, often bearing staminode-like structures or densely hirsute.

ADAPTATIONS AND ECOLOGY

• Seasonally dormant or semi-evergreen, adapting to varied climatic conditions.

• Fruit: An ellipsoid to globose berry, ripening orange to red, rarely blue or white, containing 1–few seeds.

• Seed: Ellipsoid with a smooth, thin testa; endosperm absent, embryo large and somewhat green superficially.