Description

Key Characters:

Growth Form: Climbing, twining, or rarely erect perennial herbs or shrubs some from solid, starchy, tuberous, globose to elongate, vertical or horizontal rhizomes.

Stems: Growing from fleshy, thickened, starchy rhizomes or thickened tuberous rootstocks derived from the lowest internodes of the stem and/or the hypocotyl.

Roots: Fibrous root system.

Leaves: Leaves simple or compound (palmate). Alternate or rarely opposite. Blades cordate, broadly elliptic, or occasionally palmately lobed. Base cordate. Surfaces often with embedded nectaries or mucilaginous pits, some of which contain nitrogen–fixing bacteria. Margins entire, lobed or dissected. Veins parallel or palmate or with with 3–13 curved, convergent principal veins. Long-petiolate, petioles erect, solid or rarely hollow, ribbed, glabrous, with a sheathing base, twisted or jointed at base and usually with a stipule-like flange. Stipules absent.

Flowers: Flowers in umbellate cymes on a long scape, subtended by an involucre, the bracts 4–12, but usually 4, in 2 whorls, the outer ones usually longer, persisting after anthesis, always flattened. Flowers small, unisexual (and the plants dioecious) or bisexual (perfect), actinomorphic, sometimes subtended by filiform bracts, pedicels sometimes 6–ribbed. Tepals 6, essentially all similar, dark colored, petaloid or somewhat bract-like, usually connate at base forming a short tube, the lobes in 2 alternate whorls. Stamens usually 6, in 2 whorls, the inner whorl sometimes represented by staminodes or absent; filaments distinct or connate at base, inserted on base of perianth tube; anthers dithecal, opening by longitudinal slits, often well–separated by a broad connective. Ovary inferior, 3-carpellate, 1 or 3-celled, obpyramidal, 6-ribbed; ovule placentation axial or parietal, each placenta with 2 to numerous anatropous ovules; style 1 or 3 and distinct or connate at base; stigmas with 2 or 3 lobes, each one with a stigmatic canal.

Fruit: Loculicidal capsules or a berry; often triangular or conspicuously winged. Seeds 10 to numerous; often winged; strongly ribbed; completely filling the fruit; embryo embedded in copious hard endosperm.

Ploidy:

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