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Description

As a floating herbaceous vine, it has long, branching stems containing a milky sap, with roots extending from leaf nodes. Leaves are alternate, simple, and generally arrowhead-shaped. They are 2 - 6 inches long and 0.75 - 2.25 inches wide. Petioles are 1 - 4 inches long. Flowers are white to lavender and funnel-shaped (morning-glory-like). Fruit is oval to spherical, and is 0.5 inches long and woody when mature. Fruit capsules contain 1 - 4 seeds. Water spinach can grow at a rate of 4 inches per day, producing 84 tons of fresh weight biomass per acre in 9 months. Branching stems can reach 70 feet in length.

Ecological Threat

Water spinach has created a variety of problems for fishery management, navigation, irrigation, and ecology of native plants in a number of areas around the world. Floating stands can cover the water surface shading native plants and effectively competing with native plant species. In the Philippines, water spinach is considered the second greatest problem plant.

According to the Risk Assessment for Water Spinach (Ipomoea aquatica) in Texas (Earl Chilton II, TPWD), water spinach has been cultivated in Texas for at least twenty years. Some people in the Houston area claim cultivation began in the mid-1970s with the influx of Southeast Asian refugees resulting from the war in Vietnam. During most of that time regulators were unaware of the growing industry. In 1989, Texas Parks and Wildlife Department was given legislative authority to regulate aquatic plant species, and water spinach was placed on a list of prohibited harmful or potentially harmful aquatic plants. At that time TPWD was unaware of the growing water spinach production industry, and growers were unaware of TPWD regulations. In 2003, TPWD became aware of water spinach cultivation facilities in Rosharon, Texas near Houston. At that time there were in excess of 60 growers in the area. Many of the growers were Cambodian-Americans. Primary consumers of the product were Vietnamese-Americans and Chinese-Americans. As a result of there being no evidence of establishment after approximately 30 years of commercial cultivation, TPWD modified regulations regarding water spinach in 2005 making production legal with an exotic species permit, and possession for personal consumption legal.

Biology

Water spinach may reproduce either vegetatively or by seed production. In its native India it flowers from late October to early April. In Florida, flowering occurs during warmer months. Seed production ranges from 175-245 per plant. There is evidence that germination takes place more readily on land than under water. However, reproduction is primarily by fragmentation. Nodes of existing stems can easily root and establish new plants. Both stem fragments and seeds are easily transported by water to become established in new areas. Studies have reported that the branches, with roots at each node, could each grow into independent plants.

History

First introduced in 1979 in Florida, and continues to be introduced by immigrant communities who use it as an herb rich in iron.

Native Origin

Native Origin: China

Current Location

Requires warm, humid conditions. It is a primary invader of man-made aquatic environments such as canals and ditches, and may potentially invade rice fields. Also found in natural wetlands, lakes, and river shorelines.

U.S. Present: FL, HI, PR

Resembles

It can resemble other Ipomoea species. However, there are some great native alternatives.

Alternatives: American lotus (Nelumbo lutea), White water lily (Nymphaea odorata), Floating bladderwort (Utricularia radiata).

Management

Avoid introducing this plant to local waterways. Glyphosate is effective when applied to plants in dry ditches, but will affect native species as well. 2,4-D is more selective, but little is known about is effectiveness.

USE PESTICIDES WISELY: Always read the entire pesticide label carefully, follow all mixing and application instructions and wear all recommended personal protective gear and clothing.

References

Contributions from Texas Invasives for this species page are greatly appreciated.

Bailey, L.H. and E.Z. Bailey, 1977. Hortus Third: A Concise Dictionary of Plants Cultivated in the United States and Canada, MacMillan Publishing Co., Inc., New York.

Cook, C.D.K. 1990. Origin, autecology, and spread of some of the world's most troublesome aquatic weeds. p. 31-38. In: A.H. Pieterse and K.J. Murphy (eds.), Aquatic Weeds: The Ecology and Management of Nuisance Aquatic Vegetation. Oxford University Press, New York.

Edie, H.H. and B.W.C. Ho. 1969. Ipomoea aquatica as a vegetable crop in Hong Kong. Economic Botany. 23: 32-36.

Gangstadt, E.O. 1976. Potential growth of aquatic plants in Republic of the Philippines and projected methods of control. Journal of the Aquatic Plant Management. 14: 10-14.

Holm, L., J.V. Pancho, J.P. Herberger, D.L. Plucknett. 1979. A Geographical Atlas of World Weeds. John Wiley and Sons, New York. 391 pp.

Langeland, K.A. and K.C. Burks. 2000. Identification and Biology of Non-Native Plants in Florida's Natural Areas. Gainesville: University of Florida, Institute of Food and Agricultural Sciences (IFAS). 166 pp. http://plants.ifas.ufl.edu/identif.html Accessed 5/2/03.

Palada, M.C. and S.M.A. Crossman. 1999. Evaluation of tropical leaf vegetables in the Virgin Islands. p. 388-393. In: J. Janick (ed.), Perspectives on New Crops and New Uses. ASHS Press, Alexandria, VA.

Patnaik, S. 1976. Autecology of Ipomoea aquatica Forsk. Journal of the Inland Fisheries Society of India. 8: 77-82.

Schardt, J. D., and D. C. Schmitz. 1990. 1990 Florida aquatic plant survey report. Unpublished report, Florida Department of Natural Resources, Tallahassee. 89 pp.

Internet Sources

The Quiet Invasion: A Guide to Invasive Plants of the Galveston Bay Area. Lisa Gonzalez and Jeff DallaRosa. Houston Advanced Research Center, 2006.

http://plants.usda.gov/core/profile?symbol=IPAQ

http://plants.ifas.ufl.edu/node/201