Common Morning Glory
Ipomoea purpurea
A classic garden vine that transforms fences and mailboxes into towers of vibrant trumpet-shaped flowers that open each morning and close by afternoon, a daily spectacle that has enchanted gardeners for centuries. Common Morning Glory (Ipomoea purpurea) is one of the most beloved and widely cultivated annual vines in the world — a fast-growing, self-seeding climber that produces a profusion of vivid purple, blue, pink, magenta, or white trumpet-shaped flowers from midsummer to frost, each bloom opening in the early morning and closing by midday in a daily botanical performance.
• Each flower opens in the early morning and closes by early afternoon, a circadian rhythm regulated by light and temperature that has made the plant a subject of chronobiology research
• Available in a stunning range of colors including deep violet, sky blue, pink, magenta, and pure white, often with contrasting white throats and darker midpetaline stripes
• Seeds contain ergot alkaloids including ergine (LSA), a naturally occurring compound structurally related to LSD, making them toxic and mildly hallucinogenic if ingested
• One of the easiest annual vines to grow from seed — simply nick the seed coat, soak overnight, and plant after frost for a spectacular display within 60 days
• The classic cottage garden vine, self-seeding prolifically and returning year after year in the same location without any assistance from the gardener
Taxonomy
• Naturalized throughout tropical and temperate regions worldwide, including the southern and eastern United States (where it arrived in the 17th century), southern Europe, East Asia, and Australia
• First described by Linnaeus in 1753 as Convolvulus purpureus, later transferred to the genus Ipomoea by Roth in 1821
• The genus Ipomoea is enormous, comprising over 600 species distributed across tropical and temperate regions worldwide, with the greatest diversity in the Neotropics
• Morning glory seeds were important in Aztec and other Mesoamerican religious ceremonies, where they were consumed as a sacrament under the Nahuatl name "ololiuqui"
• Introduced to European gardens by the early 18th century and quickly became one of the most popular annual climbers in cottage gardens across Britain, France, and Germany
• In Japan, morning glories (called "asagao") have been cultivated and bred for over 1,000 years, with hundreds of named cultivars developed during the Edo period (1603-1868)
• Young stems are densely hairy, giving them a fuzzy texture
• Stems twine tightly around thin supports such as string, twine, and wire
Leaves: Heart-shaped (cordate) to broadly ovate, 5-12 cm long and 4-10 cm wide, entire or shallowly 3-lobed, densely hairy on both surfaces, dark green, petioles 3-8 cm.
• Leaves are soft-textured and covered in fine hairs
• Arranged alternately along the stem
Flowers: Funnel-shaped (campanulate), 4-7 cm long and 4-6 cm across at the mouth, in shades of purple, blue, pink, magenta, or white, often with a contrasting white or pale throat and 5 darker midpetaline bands running the length of the corolla.
• Borne in axillary cymes of 3-7 flowers on peduncles 3-8 cm long
• Each flower opens in early morning (typically 5-8 AM) and closes by early afternoon
• Flowers last only a single day, but are produced in succession over months
• Flower color can be genetically unstable — some plants produce flowers of different colors on the same vine
Fruit: Globose capsule, 8-10 mm in diameter, enclosed in persistent sepals, containing 4-6 dark brown to black wedge-shaped seeds 4-5 mm long.
• Seeds are produced prolifically — a single plant can produce hundreds
• Seed pods are often ornamental in their own right
Floral Biology: The daily opening and closing of flowers is one of the best-studied examples of circadian rhythm in plants. The flowers are adapted for bee pollination — the bright colors, tubular shape, and morning opening coincide with the foraging activity of bumblebees and honeybees. The contrasting white throat serves as a landing guide for pollinators. Flowers close by midday, preventing self-pollination and encouraging cross-pollination the next morning.
Genetic Instability: The flower color genes in Ipomoea purpurea exhibit remarkable instability at the flavonoid biosynthesis locus. This results in "sectored" or "stripped" flowers where different parts of the corolla display different colors, and even flowers of different colors on the same plant — a phenomenon studied extensively by geneticists as a model for transposable element activity.
Self-Seeding: One of the most prolific self-seeding annual vines. A single plant can produce hundreds of seeds that persist in the soil for 3-5 years, creating permanent colonies that return year after year without any human assistance.
Toxicity: Seeds contain ergot alkaloids including ergine (lysergic acid amide, LSA), ergometrine, and lysergol, which are toxic and psychoactive. Ingestion causes nausea, hallucinations, and in large doses, serious medical complications.
Soil: Adaptable to most soil types but prefers moderately fertile, well-drained soil. Tolerates poor soils and actually flowers more prolifically in lean conditions — overly rich soil produces excessive foliage and few blooms. pH adaptable from 5.5 to 7.5. Avoid heavy, waterlogged soils.
Watering: Drought-tolerant once established. Water regularly during germination and early growth, then reduce watering. Overwatering promotes vegetative growth over flowering. Deep, infrequent watering encourages deep root development. Established plants rarely need supplemental water.
Temperature: Grows as a warm-season annual in temperate zones (USDA 2-11). Seeds require soil temperatures of at least 18°C to germinate. Growth is fastest at 20-30°C. Killed by the first frost. In frost-free zones, may behave as a short-lived perennial.
Sowing: Nick the hard seed coat with a file or sandpaper and soak in warm water overnight to improve germination. Sow directly outdoors after the last frost date, 1-2 cm deep. Germination in 5-14 days at 20-25°C. Do not transplant well — direct sowing is preferred. Thin seedlings to 15-20 cm apart.
Support: Provide a trellis, fence, string, netting, or teepee of bamboo poles for climbing. The twining stems need thin supports to wrap around — string and twine work better than thick poles. The vine can also be allowed to scramble through shrubs and over walls.
Care: Easy and rewarding for beginners. Minimal care required after establishment. Collect seeds from dried pods in fall for replanting next spring. Self-seeds prolifically — volunteers can be thinned or transplanted.
Fun Fact
The morning glory's daily flower opening is regulated by circadian rhythm, and flowers are typically open for only a single morning, but on overcast or cool days they may remain open until evening, giving observant gardeners an unexpected second show. • Morning glory seeds were sacred to the Aztecs, who called them "ololiuqui" and used them in religious ceremonies — when Spanish conquistadors observed the powerful effects of the seeds, they attempted to eradicate the plant, but the Aztecs protected their sacred vine by hiding cultivation in remote mountain villages • In Japan, the art of morning glory cultivation (asagao) reached extraordinary heights during the Edo period, when specialist growers developed hundreds of cultivars with flowers in every conceivable shape and color, and single plants were sold for the equivalent of thousands of modern dollars • The genetic research that earned Barbara McClintock the 1983 Nobel Prize was conducted partly on morning glory relatives, studying the "jumping genes" (transposable elements) that cause the flowers' remarkable color instability and sectoring patterns • The French Impressionist painter Claude Monet grew morning glories at Giverny, where the blue-purple flowers climbing through the trellises became subjects of several of his most famous garden paintings
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