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.
(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.