Ipomoea pes-caprae (pronounced “ip-oh-MEE-uh pess-kuh-PREE”) is a perennial vine indigenous to Hawaii like its genetic cousin Ipomoea indica (see Part 1 of this series of postings). It is known by several common names, including Beach Morning Glory, Railroad Vine, and Goat’s Foot.
Beach Morning Glory (Ipomaea pes-caprae), a common woody vine that is very salt-tolerant. Hawaiian name is "Pohuehue". Kanaha Beach, north Maui.
This last name refers to the tendency of the leaf of a mature plant to resemble the imprint left by a goat’s hoofed feet. Its Hawaiian name is Pohuehue. The plant seen most commonly in the Hawaiian Islands is a subspecies designated Ipomoea pes-caprae subsp. Brasiliensis. One of the most widely distributed beach plant species, it is found in most of the tropical and subtropical regions of the world. Its range is only limited by its inability to tolerate long-term exposure to freezing temperatures. It is present throughout the main Hawaiian Islands.
A long "runner" of "Goat's Foot" (Ipomoea pes-caprae) or Beach Morning Glory wending its way through the sun-baked sand dunes of Kanaha Beach, near Kahului, north Maui.
Habitat
Ipomoea pes-caprae is able to tolerate most soil conditions (such as excessively acidic or alkaline soils) and soil types (from sand to loam), and has a pronounced tolerance for soil-borne salt. Its favored habitat is sandy beaches and coastal sand dunes; it commonly extends its stems from the back-beach berm, over the tops of the first dunes, and right down to the high-tide mark on a beach. It is also common in back-dunes, scrub, and upland areas where it often grows along roadsides. It grows rapidly and can tolerate very high levels of salt spray. Its taproots are long and deep, often penetrating more than one meter into the substrate. It is well adapted to high-temperature conditions (as in the burning sands of tropical beaches). It also thrives in seasonally dry areas and in areas that receive heavy annual rainfall. It can recover quickly following hurricanes and tropical storms that inundate beach areas with sea water driven by heavy winds and waves. These characteristics make the Beach Morning Glory useful as a beach-stabilizing pioneer plant and ground cover.
The characteristic bi-lobed leaves of a Beach Morning Glory, also known as "Goat's Foot".
Description
The runners (stems) are succulent and contain a milky sap. They may extend outward from the woody rootstock for more than 10 m. However, the leaves on the runners are sparse, so it is rare for this species to form a very dense ground cover except in protected areas. Occasionally the creeping stems set long, thick starchy roots at intervals along their length.
Individual leaves are elliptical in shape, approximately 3-14 cm long and 2.5-12 cm wide, and are two-lobed with shallow notches at their apexes. The leaf surfaces are smooth; the upper surface has a distinctive sheen, while the under surface is duller.
The flowers are 3-16 cm in diameter, and either angular or flattened; corollas are 3-6 cm long and funnel-shaped. Color ranges from pink to reddish-purple to violet. The color tends to be darker at the inside base of each flower. Individual flowers are short-lived: they bloom at sunrise, close by mid-afternoon, and drop off the plant the following day. Small, round seedpods containing four velvety, dark-brown seeds appear on the plant after flowering.
An exceptionally long "runner" of a Beach Morning Glory (Ipomoea pes-caprae) measuring more than 8 m long. Kanaha Beach, near Kahului, north Maui.
Reproduction and Dispersal
Ipomoea pes-caprae is widely distributed throughout the tropical and subtropical regions of the world in many different habitats because it has so many different mechanisms for reproduction and dispersal. Insects attracted to the large quantities of nectar in its flowers promote cross pollination by bees, butterflies, moths, flies, beetles, wasps, and ants. This species is what is known as an obligate out-crosser: it evolved self-incompatibility, an adaptation that discourages self-pollination by an individual plant, thus ensuring good genetic diversity. Ipomoea pes-caprae also employs one of the best known examples of oceanic dispersal: it produces impermeable seeds that float and so may be carried away by wave action. The seeds are also small (6-10 mm) and lightweight enough that they are easily transported by wind-blown sand, which accounts for their presence in upland habitats some distance from coastal shores. However, because the seed coat is so tough it must be abraded by sand grains before the seed will germinate. Finally, this species also reproduces by vegetative growth, whereby even broken or damaged stem segments can take root and grow quickly in a suitable soil.
Goat's Foot and 'Aki 'Aki Grass.
Defenses
The leaves and stems of the Beach Morning Glory are protected from herbivores by the presence of harmful secondary metabolites. The stems and vine materials have a milk-colored latex in the sap, while the leaves produce a chemical compound (indole alkaloid ergotamine, a psychoactive vasoconstrictor) that protects the plant from most insects and large grazing mammals. Flowers, however, have no chemical defenses and are eaten by caterpillars, beetles, and grasshoppers.
Environmental Benefits
The Beach Morning Glory is an especially important pioneering species along tropical coastlines. Its ability to stabilize sand dunes acts a first line of defense against damaging storms. Plant stems creep over sand dunes, setting down adventitious roots, and eventually form large mats of vegetation that help prevent erosion.
Beach Morning Glory (Ipomoea pes-caprae) vines, along with Beach Naupaka and 'Aki 'Aki Grass, have stabilized this long stretch of sand dunes at Kanaha Beach, near Kahului, north Maui.
Pharmaceutical Uses
Ipomoea pes-caprae has been (and is currently) used as a medicant by practitioners of traditional medicine throughout the world. The results of modern clinical research during the last 30 years support the use of Ipomoea pes-caprae as an anti-inflammatory agent in traditional medicine. Studies have shown that laboratory preparations of the leaves of Ipomoea pes-caprae act as a significant anti-inflammatory agent, probably due to a reduction of the hormones (such as prostaglandin) responsible for histamine reactions in the body, with a potency equal to that of aspirin. The leaves and vine material may be either boiled for external application as a poultice or powdered and incorporated in an ointment. A poultice of crushed leaves and salt is still used in Hawaii to relieve the inflammation of sprains. These preparations have been used to treat various kinds epidermal ailments; for example, as an escharotic (a substance that causes tissue to die and slough off) in the treatment of ulcers, and for relief of dermatitis caused by the stings of venomous jellyfishes (the latter treatment was supported by a recent clinical study that incubated active venoms of several species of jellyfish with lab preparations of Ipomoea pes-caprae plant materials). Modern chemical analyses have indicated that the presence of naturally-occurring steroids, terpenoids, alkaloids, and flavonoids in Beach Morning Glory may account for its beneficial medicinal effects.
Tags: Beach Morning Glory, ergotamine, Goat's Foot, Ipomoea, Ipomoea pes-caprae, Pohuehue, Railroad Vine
