Taxonomic name: Merremia tuberosa (L.) Rendle
Synonyms: Batatas tuberosa (L.) Bojer, Ipomoea tuberosa L., Operculina tuberosa (L.) Meisn.
Common names: bara- asa-gao (Japanese), bejuco de golondrin (Spanish), Brazilian jalap (English), Ceylon morning glory (English), foco de luz (Spanish), Hawaiian wood rose (English), liane à tonelle (French), liane Gandelour (French), liane sultane jaune (French), liane-jaune (French), quiebra caje- te (Spanish), quiebra machet (Spanish), quinamacal (Spanish), rosa de barranco (Spanish), rose des bois (French), Spanish arborvine (English), Spanish woodbine (English), wood rose (English), xixcamátic (Náhuatl), yellow morning-glory (English)
Organism type: vine, climber
Merremia tuberosa is a climbing vine that is native to Mexico and parts of central America that has become invasive on various Pacific islands and parts of the United States. The vine overgrows tall hardwood forest canopies and smothers native trees and shrubs. Its population on Niue is reported as especially aggressive.
Merremia tuberosa is a long, climbing vine. Its leaves are simple and the blades are circular in outline, 6-16 cm long and wide, the base is cordate, and margins are palmately 5-7 lobed almost to the base. The lobes are 8-20 cm long, 9-20 cm wide, ovate, 3-9 cm long, 1-5 cm wide, and leaf margins are entire. Its stems are basally woody, perennial, twining, and glabrous. Flowers usually occur in clusters and fully bloom in sunlight and close under cloudy conditions and in the dark. The corolla is yellow, glabrous, funnelform, contortiplicate, enclosed by the sepals in bud, and comprised of 4 petals 5-6 cm long. It has 3 petioles which are 6-18 cm long and glabrous. Its pedicels are 15-18 mm long, claviform, glabrous, and enlarge in fruit. Its sepals are unequal, with the outer two longer than the inner three. They are oval to almost orbicular, with a rounded apex, membranous apically, somewhat herbaceous basally, and 23-25 mm long. Its sepals equally enlarge in fruit. The inner three are oblong, 12-20 mm long. Its filament is unequal, 2.5-3 cm long, glandular, and pubescent. The pistil is glabrous, 4-locular, and the stigma is globose. It has tuberous taproots. The fruits are globose to depressed globose and 3-3.5 cm in diameter. The calyx is accrescent, with fruiting sepals divergent but supporting the fruit. 1-4 seeds occur per fruit and are black to dark-brown, ovoid, 1.5-2 cm long, smooth surfaced, and covered with short, erect, puberulent indumentum (Austin, 1998; Motooka et al, 2003).
agricultural areas, coastland, natural forests, planted forests, ruderal/disturbed, scrub/shrublands, urban areas
Merremia tuberosa is known to grow in mesic forests from 0-1,400 m elevation. It is a climbing vine that grows over trees or other surfaces and prefers high levels of sunlight. It is also reported to require fertile, well-drained soils (Smith, undated; PIER, 2008).
Merremia tuberosa is known to overgrow and smother tall hardwood forest canopies. This perennial vine blocks sunlight from trees and the understory, killing native trees and shubs. M. tuberosa has been especially problematic on the island of Niue where it has spread quickly and aggressively (Space & Flynn, 2000). It is also reported to be toxic to animals and humans and should not be ingested by either (Smith, undated; PIER, 2005; Motooka et al, 2003; Orapa, 2003; Space & Flynn, 2000; Staples 2010).
The roots of Merremia tuberose contain resins that were formerly used across the tropics and in Europe as laxatives. Now plants are grown for their flowers and ornamental fruits that are used by florists. Its grated root was historically found useful for those that have swollen bellies and whose intestines rumble. A mixture was also drunk while fasting, to purge, and to lower fever (Austin, 1998).
Native range: Mexico, Costa Rica, Guatemala
Known introduced range: Introduced to several Islands: French Polynesia, Hawaii, Micronesia (Guam), Easter Island, New Caledonia, New Zealand, Samoa, Cook Islands, Pakistan, Sri Lanka, Taiwan, Australia and on La Réunion Island in the Indian ocean (PIER, 2008; Staples, 2010). The species is now pantropical.
Introduction pathways to new locations
Horticulture: Merremia tuberosa was spread through as a medicine throughout Europe when it was discovered in Mexico, and subsequently through horticulture trade around the world. The roots contain resins that formerly were used across the tropics and in Europe as laxatives. Now it is grown and introduced for their flowers and ornamental fruits that are used by florists (Austin, 1998).
Local dispersal methods
For ornamental purposes (local): Merremia tuberosa is a common ornamental and is used in floral arrangements. It is believed that introductions to new localities often results from discarded cuttings or seeds (Space & Flynn, 2001).
Natural dispersal (local): At least part of the dispersal of the seeds is by floating, and the seeds appear occasionally along beaches (Hemsley, 1892; Gunn & Dennis, 1976). Probably, seeds are carried locally in wet areas inland during storm runoff and in streams.
Preventative measures: A Risk Assessment of Merremia tuberosa for Hawai‘i and other Pacific islands was prepared by Dr. Curtis Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service. The alien plant screening system is derived from Pheloung et al. (1999) with minor modifications for use in Pacific islands (Daehler et al. 2004). The result is a 'High Risk' score of 12 and a recommendation of: "Likely to cause significant ecological or economic harm in Hawai‘i and on other Pacific Islands as determined by a high WRA score, which is based on published sources describing species biology and behaviour in Hawai‘i and/or other parts of the world."
Chemical: A study evaluated two types of herbicide applied by backpack sprayer for the treatment of M. tuberosa in Florida. Garlon 4 at 10% concentration applied to the basal surface of M. tuberosa was evaluated to achieve excellent control. Garlon 3A at 50% applied to cut surfaces of M. tuberosa achieved good control. Both herbicides are recommended to be applied to cut stems as it is evident which stems were effectively treated and which were missed within a week of application (Kline & Duquesnel, 1996; Langland & Stocker, 2001).
Physical: Seedlings of M. tuberosa may be hand-pulled (PIER, 2008).
Biological control: The use of a biological control for M. tuberosa has been recommended and is being investigated (Dovey et al, 2004).
Merremia tuberosa reproduces primarily through seed production and also by vegetative fragmentation. It produces an abundant seed set in the winter that germinate readily (PIER, 2008; Langland & Stocker, 2001).
Merremia tuberosa is a perennial vine that produces bright yellow morning-glory-like inflorescences in the late fall. Fruits occur abundantly in early winter. By late December and early January die backs occurs. Its seeds remain viable for several years and germinate readily even in conditions of low light (Langland & Stocker, 2001; PIER, 2008).
Reviewed by: Dr. Daniel F. Austin, Center for Sonoran Desert Studies, Arizona-Sonora Desert Museum
Compiled by: Comité français de l'UICN (IUCN French Committee) & IUCN SSC Invasive Species Specialist Group (ISSG)
Last Modified: Friday, 16 July 2010