In this genus, ornamentals and edibles abound, from edible sweet potatoes (see Sweet Potato) to trellis-climbing morning glories and the sweet potato vines that fill out container plantings so well. Native to tropical and subtropical regions of the world.
Most have hard seeds; to encourage faster sprouting, nick the coating or soak overnight in water before planting. For annual display, sow seeds in place after frost danger is past; or, for an earlier start, sow seeds indoors, then set out plants 68 in. apart. Use morning glory vines on fence or trellis or as ground cover. Or grow in containers; provide stakes or a wire cylinder for support, or let plant cascade. For cut flowers, pick stems with buds in various stages of development and place in deep vase; buds open on consecutive days.
I. alba. MOONFLOWER, MOON VINE. Perennial in TS; USDA 10-11; annual elsewhere. Fast growing (2030 ft. in a season), providing quick shade for arbor, trellis, or fence. Luxuriantly clothed in heart-shaped leaves to 8 in. long, closely spaced on stems. Blooms from early summer until fall, showing off fragrant, 6-in., funnel-shaped white blossoms after sundown and into the night (flowers also open on cloudy or dark days).
I. batatas. SWEET POTATO VINE. Perennial from tuberous roots. Zones LS, CS, TS; USDA 8-11, or indoor/outdoor plant. Annual in US, MS; USDA 6-7. For the edible sort, see Sweet Potato; the following fancy-leafed forms are grown for ornament. Trailing in habit, they have leaves that vary in size from 24 in. long, range in shape from heart shaped to deeply lobed. 'Ace of Spades' has purple-black, perfectly heart-shaped leaves; those of 'Blackie' are similar in color but are deeply lobed. 'Margarita' has golden green foliage. 'Pink Frost' ('Tricolor') has green foliage with white and pink variegation. 'Lady Fingers' has medium green leaves divided into long, fingerlike lobes; veins and leafstalks are burgundy-red. Sweet Caroline series features deeply toothed leaves available in green, bright lime-green, dark burgundy, red, and bronze (rust color). Plants in the Illusion series have dense, deeply dissected foliage in light green or purple. All of these selections look great in window boxes and hanging baskets but can overrun less vigorous companion plants. Feeding by golden tortoise beetle can riddle the leaves with holes. 'Margarita' is particularly susceptible.
I. indica. BLUE DAWN FLOWER. Perennial. Zones CS, TS; USDA 9-11. Vigorous, rapid growth to 1530 ft. Dark green, 212- to 7-in, heart-shaped or three-lobed leaves. Clusters of 3- to 4-in., funnel-shaped flowers from spring into fall; blooms open bright blue, then fade to pinkish purple by day's end. Use to cover large bank, wall, or unsightly fence or other structure. Blooms in 1 year from seed; can also be grown from cuttings, divisions, and layering of established plants.
I. lindheimeri. LINDEHEIMER MORNING GLORY. Perennial. Zones LS, CS, TS; USDA 8-11. Native from Texas to New Mexico and Mexico. Deeply cleft leaves; fragrant blue flowers to 312 in. long from spring until fall. Trailing habit, but not invasive. Well suited to dry, chalky soils.
I. lobata (Mina lobata). FIRECRACKER VINE, SPANISH FLAG. Perennial. Zones TS; USDA 10-11; grown as annual elsewhere. Grows quickly to 1015 ft. Dark green, deeply lobed leaves are 4 in. long. Bloom begins in late summer and continues until frost; flower spikes to 6 in. long are held above the foliage and carry tubular, 12- to 34-in. blossoms on just one side. Blooms start out red, then fade to orange, yellow, and finally white; 'Citronella' features lemon-yellow flowers that age to cream and white. Blossoms attract hummingbirds; also make good cut flowers. Plant in fertile, well-drained soil, and provide a post, trellis, or fence for support. Don't overdo the fertilizer or you'll get mostly leaves and few flowers.
I. xmultifida. CARDINAL CLIMBER. Annual. To 15 ft. Broad leaves to 412 in. wide, each divided into 7 to 15 sharp-pointed segments to 12 in. wide. Crimson flowers with a white eye bloom in summer.
I. nil. MORNING GLORY. Annual. Summer bloomer resembling I. tricolor, but with leaves that are often shallowly three-lobed (leaves of I. tricolor are unlobed). The large-flowered (to 6-in.-wide) Imperial Japanese strain belongs to this species; other selections include rosy red 'Scarlett O'Hara', odd pinkish tan 'Chocolate', and mixed-color Early Call strain. Flowers of 'Tie Dye' are white with bold stripes and splashes of blue or pink.
I. pes-caprae. BEACH MORNING GLORY, RAILROAD VINE. Evergreen perennial. Zones CS, TS; USDA 9-11. Native to Florida. Sprawling vine grows to great length, rooting at leaf joints as it runs. Medium green leaves are fleshy, 1124 in. long, notched at the tip, and nearly round to kidney shaped. Pink summer flowers to 2 in. wide. Useful as a ground cover on sandy saltwater beaches.
I. purpurea. COMMON MORNING GLORY. Perennial in TS; USDA 10-11; annual elsewhere. Like I. tricolor but generally has smaller leaves and flowers. Blooms in summer. Rapid growth to 30 40 ft. Medium green leaves are broadly oval and pointed, three lobed or unlobed. First flowers appear a few weeks after sowing seed; then vine quickly covers itself in 5-in.-wide purple, blue, white, and pink blooms with pale throats, especially showy because of their many colors. Water and fertilize sparingly during summer to encourage flowers. Reseeds and returns in spring; watch that it doesn't escape and become a nuisance. 'Grandpa Otts' and 'President Tyler' are deep purple with a rosy red, star-shaped overlay and white throat; 'Milky Way' is pure white with a maroon star. 'Crimson Rambler' has bright red, white-throated blooms.
I. quamoclit. CYPRESS VINE. Annual. To 20 ft., with 212- to 4-in.-long, dark green leaves finely divided into slender threads. Summer flowers are scarlet (rarely white), 112-in.-long tubes that flare at mouth into a five-pointed star.
I. tricolor. MORNING GLORY. Annual. Vigorous growth to 1015 ft., with large, heart-shaped leaves in light to medium green. Showy, funnel-shaped to bell-like flowers are single or double, in solid colors of blue, lavender, pink, red, or white, often with throats in contrasting colors; some are bicolored or striped. Most types open only in morning, fade in afternoon. Bloom from summer until frost. Among the most popular selections is 'Heavenly Blue', to 15 ft., bearing 4- to 5-in., pure sky-blue flowers with yellow throat. 'Wedding Bells' is similar, but with rosy-purple blooms. 'Flying Saucers' has 4- to 5-in. white blossoms variably streaked with purplish blue. Dwarf strain with white markings on the leaves (known as Spice Islands or simply as Variegated) grows only 9 in. high and spills to 1 ft. across; flower colors include red, pink, blue, and bicolors.