6. Ipomoea (morning glory)

Plants annual or perennial herbs (woody elsewhere), usually scrambling or twining, sometimes with tuberous root systems. Stems sometimes somewhat angular, glabrous or hairy. Leaves short- to long-petiolate. Leaf blades variously shaped, most commonly triangular-ovate or heart-shaped, often with 1 pair of triangular lobes at the base (pinnately dissected into numerous linear lobes in I. quamoclit; palmately lobed or compound elsewhere), bluntly or sharply pointed at the tip, truncate to more commonly deeply cordate at the base, the margins otherwise entire or less commonly somewhat wavy or few-toothed. Inflorescences axillary, the flowers solitary or in loose clusters, long-stalked. Bracts variable, sometimes absent, often only at the inflorescence branch points, when present inconspicuous and scalelike, usually distant from, always much shorter than, and not covering the calyx, usually not overlapping, linear to ovate, often shed before fruiting. Calyx of free sepals, these similar in size and shape or unequal, 9–25 mm long, often overlapping, variously shaped, herbaceous or thickened and somewhat leathery, glabrous or variously hairy. Corollas very shallowly 5-lobed, funnelform or trumpet-shaped, white to pink, red, purple, or blue. Stamens lacking subtending scales, sometimes somewhat exserted. Ovary 2–4-locular, with 4 ovules. Style 1, the stigma 1, capitate, sometimes 2- or 3-lobed. Fruits globose to ovoid, 2(4)-locular, dehiscing longitudinally, the wall separating into usually 4 segments. Seeds 1–4, oblong-ovate to ovate in outline, somewhat longitudinally angled on the inner face, the surface smooth to very finely granular, tan to dark brown or black, glabrous or hairy. Five hundred to 650 species, nearly worldwide.

Ipomoea is most diverse in tropical and warm-temperate areas. The economically most important member of the genus is I. batatas L. (sweet potato), a cultigen of tropical American origin that is grown as a starchy vegetable in warmer regions around the world for its sweet, tuberous roots. A number of species also are cultivated as ornamentals, in Missouri usually as annuals on fences and trellises. Several species are important agricultural weeds. The seeds of various species contain significant quantities of hallucinogenic ergoline alkaloids; those of some species also have been used medicinally for their purgative properties.

Steyermark (1963) reported an introduced occurrence of I. cairica (L.) Sweet, based on a single collection by Viktor Mühlenbach (1979) from the St. Louis railyards. This native of Africa differs from other Missouri morning glories in its leaves, which are deeply palmately lobed or compound with 3–7 lobes or leaflets (Pl. 367 h). However, the specimen documenting this find could not be located during the present research and may have been discarded. Because the species has not been rediscovered in Missouri and the original find remains undocumented, this species is excluded from the state’s flora for the present.