VITACEAE (Grape Family)

Plants vines, usually lianas, with tendrils (except occasionally in Vitis rupestris) positioned opposite leaves and sometimes also in the inflorescence, these often branched (except in Cissus and Vitis rotundifolia), lacking thorns or spines, sometimes incompletely or nearly completely monoecious or dioecious. Stems often swollen at the nodes. Leaves alternate, simple or compound, short to more commonly long-petiolate. Stipules small, scalelike, shed before the leaves mature. Inflorescences compound umbels or panicles of small flowers. Flowers perfect or functionally staminate or pistillate, hypogynous, actinomorphic. Calyces fused into a low spreading collar, this sometimes shallowly 4- or 5-lobed. Corollas of mostly 4 or 5 petals, these free or (in Vitis) fused at the tips. Stamens mostly 4 or 5 (produced but somewhat reduced and nonfunctional in pistillate flowers), opposite the petals, the anthers minute, attached near their midpoint. Nectar disc present, unlobed or the lobes alternating with the stamens (reduced and fused to the ovary in Parthenocissus). Pistil 1 per flower (reduced and nonfunctional in staminate flowers), of usually 2 fused carpels. Ovary superior (but sometimes appearing somewhat sunken into the nectar disc), 2-locular, each locule with 2 ovules, the placentation more or less basal. Style 1, the stigma minute, unlobed or slightly 2-lobed. Fruits 1–4-seeded berries, globose to obovoid. Eleven to 14 genera, 700–850 species, nearly worldwide, most diverse in tropical regions.

Seeds of the subfamily Vitoideae, which includes all of the Missouri genera, are distinctive. They vary in shape depending upon the number in the particular berry, but all have a broadly convex dorsal surface and a longitudinally angled inner surface. The angle of the inner surface has a pair of slender longtiudinal grooves along its spine that wrap around to the dorsal surface and encircle in a well-marked circular to teardrop-shaped plate known as a “chalazal knot.” This distinctive feature allows ready familial determination of seeds, even from archaeological sites or the fossil record.