Morning Glories

Wayne's WordIndexNoteworthy PlantsTriviaLemnaceaeBiology 101BotanySearch

WAYNE'S WORD Volume 8 (Number 4) Winter 2000

Morning Glories

The World's Most Beautiful Vines

Modified From: Pacific Horticulture 58: 15-21
by Wayne P. Armstrong (Spring 1997)

Table Of Contents:

  1.  Introduction
  2.  California Morning Glories
  3.  Cultivated Morning Glories
  4.  Water Spinach Morning Glory
  5.  Sweet Potatoes & Columbus
  6.  Irish Potatoes & Columbus
  7.  Sweet Potatoes In Polynesia
  8.  True Dioscorea Yams
  9.  Hallucinogens
10.  Fabulous Mary's Beans

1. Introduction

The Morning-Glory Family (Convolvulaceae) contains at least 50 genera and more than 1000 species, from high-climbing vines and woody lianas of the tropical rain forest to prostrate, trailing perennials. They decorate our fences, trellises and walls with lush green foliage and colorful funnel-shaped blossoms, and form lovely green carpets of dichondra lawn. Several vines of this family provide us with valuable and nutritious root crops, including a Mexican jicama and sweet potatoes. [Note: The common supermarket jicama sold in the U.S. comes from the leguminous vine Pachyrhizus erosus (Fabaceae) from Mexico and Central America.] Although the Morning-Glory Family is usually associated with climbing vines, it also includes erect herbs, shrubs and a few trees. One unusual genus includes the parasitic dodders (Cuscuta) which smother their host with masses of twining, spaghetti-like orange stems. Other morning glories have invaded cultivated fields and have become troublesome weeds. Called "bindweeds," they literally twine themselves over other plants that happen to be in their growth path. Some morning glories are excellent seed voyagers and have colonized the distant beaches of tropical islands and atolls throughout the world.

The lovely "blue dawn-flower" (Ipomoea acuminata), also known as I. learii. According to the famous horticulturist L.H. Bailey (1928), this prolific South American perennial morning glory may produce 60,000 flowers at the rate of 300 per day.

Species of morning glories are probably most abundant in tropical America and Asia, although they also grow in subtropical and temperate regions. Vine and liana seedlings grow fast in the tropics and often get their start at the forest edge or in gaps where trees have fallen and sunlight floods in. With the intense competition for space and light, growing rapidly to the tops of trees where leafy "solar panels" can photosynthesize is a marvelous adaptation. Although morning glories belong to dozens of different genera with slightly different floral, fruit and leaf characteristics, they all produce typical funnel-shaped blossoms in white, red, blue, purple and yellow. The flowers often show pleats or crease marks where the corolla was neatly folded or rolled up in the bud.

2. Native Morning Glories In California

The Morning-Glory Family is well-represented in California with five genera and 23 native and naturalized species. The largest genus is Calystegia, including 12 species of white-flowered morning glories that adorn shrubs and canyon walls in the chaparral and pine forests. Species of Calystegia are separated from their former genus Convolvulus by a slightly larger corolla and calyx, with stigma lobes that are slightly flattened. Unless you have seen representative examples of both genera, separating them using a taxonomic key can be somewhat exasperating. The Jepson Manual of Higher Plants of California (1993) lists 20 subspecies of Calystegia, including six for the common chaparral morning glory C. macrostegia, so consider yourself very fortunate if you can key one down to its subspecific level. A distinctive pink-flowered species with kidney-shaped, fleshy leaves (C. soldanella) is occasionally found along sandy seashores of the Pacific coast. This interesting species has an international distribution, and also grows on beaches of Europe and South America.

A wild beach morning glory (Calystegia soldanella) growing at Silver Strand State Beach in San Diego County, California. This widespread species also grows on beaches of Europe and South America.

Another unusual native California species is the woolly morning glory (C. malacophylla ssp. pedicellata), occasionally found in the Coast Ranges and Mount Pinos region. Cultivated fields and vacant lots often contain a sprawling white-flowered morning glory in the closely related type genus Convolvulus called bindweed (Convolvulus arvensis). It has earned the name "bindweed" from its habit of twining around other plants, including cultivated crops. Like many other weedy species, bindweed is actually native to Eurasia, but has become well-established in California. A little-known native bindweed (called clay bindweed) with minute white flowers (C. simulans) is occasionally found on slopes and mesas with heavy clay soils. Because of the extensive land development in coastal southern California, where fields of native wildflowers are rapidly being converted into high density housing tracts, species such as the unusual clay bindweed are disappearing from the landscape forever.

Clay bindweed (Convolvulus simulans), a diminutive morning glory occasionally found in heavy clay soils on slopes and mesas of California. Note the minute flowers to the left of the U.S. penny (one cent). This unusual little morning glory is rapidly disappearing from the southern California landscape due to rapid urbanization.

Native California and the Channel Islands also have a native Dichondra occidentalis that grows in shady soils beneath thickets of coastal sage scrub and chaparral, and a small white-flowered perennial (Cressa truxillensis) that commonly grows in salt marshes along the coast. The state also includes eight native species of parasitic dodders (Cuscuta), often confined to one or a few host species. The dodders are often placed in a separate family, the Cuscutaceae. Although dodders resemble tangled masses of orange, spaghetti-like strands twining over shrubs, they actually produce miniature versions of a typical morning glory flower. The dodder taps in on its host's nutrient supply with a modified root structure called a haustorium. It has been estimated that the total length of twining branches produced by a single dodder plant may exceed half a mile. One remarkable species (C. marina) is tolerant of brackish water and parasitizes salt marsh plants such as Salicornia and Chenopodium along coastal estuaries. A very similar-appearing dodder on many Caribbean islands is Cassythia filiformis of the different and unrelated Laurel Family (Lauraceae), an extraordinary example of convergent evolution in which a single genus in each family has developed a parasitic mode of life.

Calystegia macrostegia ssp. intermedia, a common white-flowered morning glory native to coastal hillsides and grassland areas of San Diego County, California. This subspecies intergrades with several other white-flowered subspecies in San Diego County, making their precise identification very difficult (especially in the field).

3. Cultivated Morning Glories In California

The most commonly cultivated morning glories belong to the genus Ipomoea, climbing vines bearing a profusion of blue funnel-shaped blossoms with white or yellow centers. During the summer months, fences, trellises and abandoned sheds become showy mounds of sky blue Ipomoea blossoms. Red and white sweet potatoes are cultivated varieties of Ipomoea batatas, a tropical American morning glory that was discovered by Columbus. In fact, the sweet potato is hexaploid (with six sets of chromosomes) and may have arisen by hybridization and polyploidy of wild, tuberous Central American morning glories such as I. trifida and I. tiliacea. Some of the most commonly grown morning glories in California are the Mexican and South American I. acuminata (I. learii), I. purpurea, I. triloba, and I. cairica (I. palmata). Some of these species are very invasive and may become naturalized in orchards, vacant fields and canyons, particularly the perennial species in mild coastal areas. For example, I. cairica can readily be identified by its palmately compound leaves, and forms extensive mats in coastal central and southern California. According to the famous horticulturist L.H. Bailey (1928), the prolific South American perennial morning glory called "blue dawn flower" (I. acuminata) may produce 60,000 flowers at the rate of 300 per day. When the blossoms first open in the early morning hours they are a beautiful deep blue color. Throughout the Caribbean islands, high-climbing, rampant morning glories, such as I. tiliacea and I. hederacea, adorn roadside banks and trees with masses of purple and blue blossoms. The seeds of some Ipomoea species are well-adapted for floating long distances in ocean water. The trailing vine I. pes-caprae, often called beach morning glory or railroad vine, has colonized sandy beaches throughout the tropics, including many Caribbean islands and the Galapagos Archipelago off the coast of Ecuador.

Ipomoea cairica (I. palmata), a showy, perennial morning glory with palmately compound leaves. Although native to South America, it has become naturalized in moist creekbeds of coastal California.

4. Water Spinach: An Aquatic Morning Glory

Water spinach (Ipomoea aquatica) is an aquatic morning glory native to China. It is a popular cutivated green vegetable in China, India, Malaysia, Africa, Brazil, the West Indies, and Central America. It is sold in Asian markets in southern Califonia under the name of "on-choy" or "ong-chow" and is also served in some Asian restaurants. Water spinach is a creeping, herbaceous vine with alternate leaves arising from buoyant, hollow stems that root at the nodes. A single plant can branch profusely with floating stems that form dense mats on the water surface. With a growth rate of approximately four inches (10 cm) per day, water spinach poses a significant threat to flood control and native habitats, especially in central and southern Florida. It forms dense, impenetrable canopies over small ponds and basins, creating stagnant water conditions that are ideal breeding environments for mosquitoes.

Although it is a tasty vegetable, it has become a prolific naturalized weed in Africa, Australia, the Pacific Islands and South America. Due to its aggressive growth rate, water spinach has the potential to invade moist cultivated areas, such as rice and sugar cane fields, and wetlands such as the Everglades, natural lakes and rivers, drainage canals and ditches. In Florida, isolated populations have been found floating and creeping horizontally along shorelines and over water for long distances, especially in lakes and canals. It can displace native plants that provide the vital habitats for fish and wildlife. In Florida, the possession of water spinach is prohibited without a special permit issued by the Florida Department of Environmental Protection.

Water spinach (Ipomoea aquatica), an aggressive water plant native to China and naturalized throughout many tropical and semitropical regions. Although it is an invasive weed, it is also an important green vegetable in Asian cuisine. The creeping stems are hollow and float on the water surface.

5. Sweet Potatoes and Columbus

Although rarely flowering in the Pacific states, the sweet potato is one of the most fascinating species of Ipomoea. The sweet potato was definitely mentioned in records from Columbus' fourth voyage to the Caribbean region in 1502, and was probably encountered on his previous voyages. According to S.E. Morison (Journals and Other Documents on the Life and Voyages of Christopher Columbus, 1963), the "chestnutty root" called "mames" which was tasted by Columbus on his first voyage was probably cassava (Manihot esculenta); however, Björn Landström (Columbus, 1966) claimed that the root which the Indians called mames was indeed the sweet potato.

Three New World root crops: Top, Jicama (Pachyrhizus erosus), a member of the Legume Family (Fabaceae); lower left and right, white and red sweet potatoes (Ipomoea batatas). The red sweet potatoes are often called "yams" in the United States, not to be confused with the true yams of the large tropical genus (Dioscorea).

6. Irish Potatoes and Columbus

Columbus is also credited with bringing the white or Irish potato (Solanum tuberosum), a member of the Nightshade Family (Solanaceae), back to Spain, although most scholars argue that his reference to potatoes or "batatas" indicated sweet potatoes rather than the Irish potato. Other Spanish explorers found true potatoes (called "papas") being grown by Indians all along the Andes from Colombia to Chile, and potatoes were known in Spain after 1565. Later, potatoes were introduced into the British Isles where they were grown extensively by the early 1800s. In fact, potatoes were so popular in Ireland that they became known as Irish potatoes even though their origin was South America. Ireland developed a monoculture of potatoes until the mid 1840s when their entire crop was devastated by the potato blight fungus (Phytophthora infestans). It has been estimated that during a five year period at least a million people died of starvation. The potato famine set into motion a wave of emigration that reduced Ireland's population by 50 percent between 1846 and 1900. The Irish constituted 35 percent of the immigrants to the United States during this period and became 15-18 percent of the population.

7. How Did Sweet Potatoes Get To Polynesia?

Because sweet potatoes thrive in a hot, moist climate, while potatoes require a cool climate, they have never become as popular as the Irish potato in Europe. Sweet potatoes have become an important root crop in warm subtropical and tropical countries, second only to cassava or manioc (Manihot esculenta), a member of the Euphorbia Family (Euphorbiaceae) and the source of tapioca. Archaeological evidence shows that sweet potatoes were cultivated in South America by 2400 B.C. and fossilized sweet potatoes from the Andes have been dated at 8,000 to 10,000 years old. Although the sweet potato is clearly native to South America, it was also cultivated in Polynesia as early as 1200 A.D. In fact, the sweet potato had already become the principal food of the Maoris in New Zealand by the time of Captain Cook's historic voyage to that part of the world in 1769. It is interesting to note that the sweet potato is known as "kumar" or "kumal" in the Lima region of Coastal Peru, and it is called "kumara" by the Maoris of New Zealand. In his book, Sea Routes to Polynesia (1968), Thor Heyerdahl postulated that sweet potatoes were carried across the Pacific by Peruvian Indians before Europeans began to sail the world's oceans. He tested his hypothesis in 1947 by sailing a balsa wood raft, the kon-tiki, fashioned after the reed rafts of the Oru Indians living on Lake Titicaca in Bolivia. Although Heyerdahl's hypothesis about the transoceanic exchange of sweet potatoes by skillful pre-columbian sailors remains an enigma (at least to some skeptics), his New World origin for the coconut (Cocos nucifera) has been rejected by most botanists. Widespread sea dispersal of wild-type coconuts, the remarkable dispersal of coconut crab larvae riding on coconuts, and fossil evidence of Miocene coconuts in the South Pacific indicate an Indo-Pacific origin, long before the voyages of ancient mariners. Most authorities now agree that the coconut was introduced to the New World by Portuguese and Spanish traders.

8. Sweet Potato Yams Vs. True Yams

Unlike the stem tubers of Irish potatoes, sweet potatoes are fascicled (clustered) storage roots. Irish potatoes are propagated by planting sections of the tuber containing an "eye" or bud. Sweet potatoes do not have "eyes" and cannot be propagated by planting pieces of the root in the ground. There are a number of cultivated varieties of sweet potatoes, including dry, white-fleshed varieties and moist, red-fleshed varieties. The soft, red-fleshed sweet potatoes are erroneously called "yams" in the United States. The flesh of yellow or orange-fleshed "yams" have a beta carotene content almost as high as carrots and are generally more relished in the southern United States. Actually, true yams belong to the genus Dioscorea from an entirely different plant family, the Diosoreaceae.

See True Potatoes In The Nightshade Family

Although rarely seen in the United States, true yams (Dioscorea species) are the third most important tropical root crop after cassava and sweet potatoes. They are climbing perennial vines with large underground stems that are technically called tubers rather than roots. Like the Irish potato, the tubers can be propagated by planting sections containing the buds; however, harvesting them is a laborious task because the tubers are deeply buried. Dioscorea is a large genus with more than 600 species. One African species, called elephant's foot or Hottentot's bread (D. elephantipes) produces a huge underground tuber weighing up to 700 pounds. The woody, above-ground part of this enormous tuber resembles the shell of a tortoise--hence the common name of "turtleback plant." Another unusual African yam is the air potato (D. bulbifera). It has small or no subterranean tubers, but instead develops large, liver-shaped aerial tubers up to four pounds each. Tropical yams may be more than six feet long and weigh up to 150 pounds, although they are usually harvested at about two to six pounds. They are definitely the undisputed world's largest vegetable, excluding pumpkins and squash which are technically botanical fruits.

See Dioscorea Yam: World's Largest Vegetable

In addition to providing a nutritious, starchy food source, several species of true yams are rich in the natural steroid diosgenin, a precursor for important synthetic steroids including the sex hormones progesterone and testosterone, the anti-inflammatory steroid cortisone, and the potentially harmful anabolic steroids used by some body builders. In fact, more than 60,000 tons of fresh yam tubers (including D. composita and D. floribunda) are imported into the United States each year for the production of birth control pills.

Although not as large as true yams, some perennial morning glories produce large, woody taproots capable of surviving prolonged drought conditions. The popular vegetable called jicama (Exogonium bracteatum) comes from the large fleshy, taproot of a vine native to arroyos of the Cape region of Baja California and mainland Mexico. This species was once placed in the genus Ipomoea. [Note: The common supermarket jicama sold in the U.S. comes from the leguminous vine Pachyrhizus erosus (Fabaceae) from Mexico and Central America.] Another remarkable species I. platensis is native to dry regions of Argentina. Like xerophytic plants of other desert regions, it produces swollen, caudiciform stems that store water and can survive extended periods of drought.

Ipomoea platensis, a remarkable morning glory native to arid regions of Argentina. Like other "caudiciform" species, it has swollen stems containing water-storage tissue, and can survive extended periods of drought. [Photographed by author (Mr. Wolffia) at the fabulous Huntington Botanical Garden in San Marino, California.]

9. Hallucinogenic Morning Glories

Seeds of two infamous Mexican morning glories, Ipomoea tricolor (I. violacea) and the white-flowered Turbina corymbosa, were taken in a drink by Aztec priests in order to commune with their gods. Because of the extremely fine line between effective and lethal doses, the ground seeds were only ingested by experienced persons. The seeds from these two morning glories are called ololiuqui (pronounced o-low-lee-oo-key) by native Indians of Mexico, and provide them with an important medicinal and religious ritual in their cultures. According to Richard Evans Schultes and Albert Hofmann (Plants of the Gods, 1979), the seeds contain a lysergic acid alkaloid called ergine (d-lysergic acid amide), better known as "natural" LSD. [The more potent synthetic LSD is d-lysergic acid diethylamide.] Before it was discovered in morning glories, ergine was only known from ergot (Claviceps purpurea), a rust fungus that infects grains. During the Middle Ages, thousands of people in Europe were afflicted with ergotism, a malady characterized by gangrenous extremities, convulsions and madness. They ate rye bread infested with ergot fungus containing ergine and several potent vasoconstricting (blood vessel-constricting) alkaloids. Known as "St. Anthony's Fire," it was a dreaded disease. Psychoactive alkaloids, such as ergine and psilocybin (from the mushrooms Psilocybe mexicana and Stropharia cubensis), contain the indole structure, a double carbon-nitrogen ring also found in the natural neurotransmitter serotonin. These alkaloids may interfere or compete with the action of serotonin in the brain. Another strong hallucinogenic alkaloid, mescaline, comes from the Mexican peyote cactus (Lophophora williamsii and the commonly cultivated South American San Pedro Cactus (Trichocereus pachanoi). Mescaline has a chemical structure remarkably similar to the brain neurotransmitter dopamine. Contrary to popular rumors, mescaline is not found in the fermented Agave beverage known as Mezcal or in the bright red, poisonous seeds of the beautiful, drought-resistant shrub called mescal bean (Sophora secundiflora). The latter seeds contain another potent and dangerously poisonous alkaloid, cytisine, which was ingested by some North American Indian tribes in a ceremonial "Red Bean Dance" prior to the widespread use of peyote.

See Article About Hallucinogenic Morning Glories
Photos Of Hallucinogenic Morning Glories

For Indians of Mexico, Central and South America, partaking of these hallucinogenic alkaloids from mushrooms and native plants was a deeply religious experience, enabling them to communicate with their gods. Other well-known hallucinogens include the bright red fly agaric mushroom (Amanita muscaria) and several native species of jimsonweed (including Datura wrightii). Some scholars believe that the original story of Alice's Adventures in Wonderland, where Alice speaks to a green caterpillar seated on a red and white-capped mushroom, is actually the interpretation of a mushroom experience by the author, Rev. C.L. Dodgson of Christ Church College in Oxford (better known by his pen name of Lewis Carroll). Another popular hallucinogenic "high" depicted in paintings and children's stories is the infamous, politically incorrect picture of a witch flying on a broom, the effects of a potion made from the deadly alkaloids of several solanaceous herbs, including Datura stramonium.

See Article About Plant Alkaloids

10. The Marvelous Merremias--Including The Mary's Bean

Some of the most interesting morning glories belong to the genus Merremia, twining vines with tuberous roots and beautiful yellow blossoms. Merremia species differ from Ipomoea chiefly in having smooth rather than spiny pollen grains, a trait that can be observed with a good hand lens. During the late spring and summer in the scenic Cape region of Baja California, the endemic M. aurea decorates the native vegetation with striking golden trumpets. A similar species (M. tuberosa) grows in the Hawaiian Islands and throughout the tropics. Known to Polynesian travelers as the "wood rose," the enlarged, dried calyx surrounding the seed capsule resembles a lovely rose carved in wood and polished to a satiny-brown finish. Inside the papery capsule are four black seeds that neatly fit together like a cake cut into four sections. Another rampant South American perennial known as Alamo vine (M. dissecta) is naturalized from Georgia to Florida and Texas.

Hawaiian wood roses (Merremia tuberosa) are the dried flowers (calyx and seed capsule) of a high-climbing pantropical morning glory. Each capsule contains a cluster of four black seeds.

The golden-yellow blossoms of "yuca" (Merremia aurea) decorate the desert scrub in southern Baja California. This lovely morning glory is endemic to the Cape Region and several Gulf Islands.

But of all the members of the Morning-Glory Family, perhaps the most fascinating is the Mary's bean (Merremia discoidesperma). The Mary's bean comes from a little-known tropical vine or liana native to southern Mexico and Central America. Named after the Virgin Mary, it is also called crucifixion bean because of a cross etched on the dorsal side of the seed. The ventral side has a large, oval attachment scar (hilum). The cross is actually an impression where the seed was attached inside the capsule. Part of the cross is produced by the impression of a narrow, black strap that is connected at each end of the hilum. The strap wraps around the dorsal side of the large seed and holds it in the papery capsule. The groove produced by the connecting strap intersects with another indentation, thus forming the distinctive imprint of a cross. In all other Merremia species, the cross is divided into a tetrad of four small (separate) seeds. In fact, when all four seeds from a wood rose capsule are placed together they are roughly the size and shape of one Mary's bean. New Mary's bean seeds still enclosed in their capsules are covered with a dense layer of black hairs. The fuzzy covering eventually wears off exposing the dark brown-black, woody seed coat that is impervious to water. The thick seed coat and internal air cavities enable the buoyant seeds to drift for months or even years at sea. Historically, people have used Mary's beans as good luck charms and to ward off evil spirits. A woman in labor was assured an easy delivery if she clinched a Mary's bean in her hand, and the seeds were handed down from mother to daughter as treasured keepsakes. The seeds have also been used as an antidote for snake bites in Nicaragua and as a cure for hemorrhoids in Mexico. The hemorrhoidal treatment requires the sufferer to carry a "male" and a "female" seed in their back pocket. Apparently the sex of a seed is determined by whether they float or sink in water. According to the "Flora of Guatemala" by P.C. Standley and J.A. Steyermark (Fieldiana Vol. 24, 1946), "male" and "female" seeds from another leguminous rain forest liana Mucuna argyrophylla are carried by natives to prevent hemorrhoids. Those that sink in water are called "hembras" (female) and those that float are "macho" (male). They are also called ojo de venado (deer eyes) and "sea beans" because, like the Mary's bean, they often become drift seeds. To this day, Mary's beans are sometimes sold by street vendors in Costa Rica, although I am not sure which of the above purposes they are used for. Throughout beaches of the Old and New World, the Mary's bean is always a treasured discovery for beachcombers lucky enough to find one.

In its native habitat, the Mary's bean vine or liana is only known from a few locations in the rain forests of Mexico and Central America. In the rain forest near Golfito, Costa Rica, scattered Mary's bean vines hang from the trees, forming dense curtains of leafy stems typical of morning glory vines. Other woody lianas of the legume family (Fabaceae) also grow in the area, including several species of sea beans (Mucuna) and the amazing sea heart (Entada gigas). The latter leguminous vines also produce remarkable sea-faring seeds. The seeds of these lianas commonly get washed down rivers where they drift out to sea. The sea heart is especially interesting because the large, woody, heart-shaped seeds are produced in a pod three to six feet long (the world's largest legume). Some historians believe that sea hearts collected on the beaches of the Azores (off the coast of Portugal) provided inspiration to Columbus and led him to set forth in search of new lands to the west. As a drift seed, the Mary's bean is known from Wotho Atoll in the Marshall Islands to beaches of Norway, a total distance or more than 15,000 miles. According to the world authority on drift seeds, Charles R. Gunn (Economic Botany Vol. 31, 1977), this is the widest drift range documented for any seed or fruit. Other pantropical seeds (such as sea beans and sea hearts) may drift as far or farther, but their precise point of origin cannot be determined. The Mary's bean is unmistakable among drift seeds and its origin is well documented. If you find one, it must have ultimately come from the rain forests of southern Mexico and Central America.

Go To Article About The Mary's Bean
Go To Article About The Sea Heart

Morning glories have many special meanings to different people. They decorate our world with beautiful flowering vines and provide us with some nutritious and delicious vegetables. To native Indians of Mexico they are truly spiritual plants that connect them with their ancestors. And to a beach-comber, a Mary's bean may brighten up your life if you happen to discover this most unique and truly remarkable seed.

Return To WAYNE'S WORD Home Page
Go To Biology GEE WHIZ TRIVIA Page