3. Ipomoea hederacea Jacq. (blue morning glory, ivy-leaved morning glory)

I. hederacea var. integriuscula A. Gray

Pl. 368 h–j; Map 1598

Plants annual. Stems 30–250 cm long, moderately to densely pubescent with relatively long, spreading to downward-angled hairs. Leaves long-petiolate. Leaf blades 2–12 cm long, unlobed or more commonly deeply 3(5)-lobed, the lobes triangular, broadly ovate to ovate-triangular in overall outline, tapered to a sharply pointed tip, shallowly to more commonly deeply cordate at the base, both surfaces moderately pubescent with straight, appressed to spreading hairs, the margins otherwise entire. Flowers solitary or more commonly in loose clusters of 2 or 3(–6), the stalks moderately to densely pubescent with relatively long, spreading to downward-angled hairs. Sepals similar in size and shape, 12–25 mm long, with a short, ovate basal portion and an outward-curled, long-tapered, sharply pointed, linear tip, the surface and margins moderately to densely pubescent with relatively long, spreading to downward-angled hairs. Corollas 2.5–5.0 cm long, funnelform to slightly bell-shaped, the tube widened gradually toward the tip, purple or light blue with a white or yellowish white center. Stamens not exserted. Ovary 3-locular, the stigma 3-lobed. Fruits globose or slightly depressed-globose, the main body 8–12 mm long, the persistent style 4–15 mm long, glabrous. Seeds 4–5 mm long, the surface moderately to densely minutely hairy. 2n=30. July–October.

Introduced, common throughout the state (native probably of tropical America, now widely introduced in the U.S. and adjacent Canada [and other warm-temperate to tropical portions of the world] west to North Dakota and Arizona). Banks of streams and rivers; also crop fields, fallow fields, gardens, pastures, fencerows, ditches, railroads, roadsides, and open, disturbed areas.

Ipmoea hederacea and I. purpurea were confused in some of the older botanical literature but were treated correctly by Steyermark (1963). Both are weedy species with variable leaf shapes. Elmore (1986) performed controlled crosses between entire-leaved and 3-lobed (ivy-leaved) lineages of I. hederacea. He concluded that leaf lobing is controlled by a single gene, with the lobed genotype (which is more common in Missouri) dominant over the unlobed one. The recognition of varieties based upon this minor variation is thus unwarranted. There is some controversy as to the natural range of the species, with most authors postulating a neotropical origin. However, Austin (1990) and others have suggested that I. hederacea originally was endemic to the southeastern United States. The species’ spread as a contaminant in agricultural products was early enough that it may not be possible to discern its native provenance with any certainty.