Traveling around the globe in seventy years, Salvinia molesta (giant salvinia)
has adopted a far ranging distribution from a limited native range.
Native Range: The coastal region of southern Brazil, between latitudes 24 and 32° S, and inland to elevations of 900 m (Forno and Harley 1979; Forno 1983). In its native range S. molesta is not especially abundant.
Global Range: Increased widely since the 1930’s when first introduced to Sri Lanka. Salvinia molesta has become established in tropical and subtropical regions of South Africa, Sri Lanka, India, Southeast Asia, Indonesia (especially Java), Malaysia, Papua New Guinea, Australia, and the North Island of New Zealand. Plants typically grow in enormous proportions over slow moving rivers and lakes in the introduced regions. In southern Kalimantan (formerly Borneo), rainy season flooding annually distributes plants from rivers and swamps to lowland rice fields [(J. Petta s.n. (FLAS)].
(mouse-over species above)
Predicted U.S. Range: The Atlantic Coastal Plain, from southeastern Virginia through Florida, west across the Gulf Coast states; Arizona to central California. Salvinia molesta may be expected to establish wherever Eichhornia crassipes (water-hyacinth) persists. Water-hyacinth is well established in the southern states of North America after it was first introduced over a hundred years ago. The established range of water-hyacinth includes zones 10, 9 and 8 of the USDA Plant Hardiness zone map. Water hyacinth extends into zone 7d and generally follows that path as its northern range limit. Waif populations of water-hyacinth, those only fleetingly established and probably not permanent, are known to extend farther, at the least into zone 7a. Salvinia minima (common salvinia) extends into zone 7b in Arkansas and zone 7a in Texas. Giant salvinia has survived and persisted well in zone 7d, namely in North Carolina and Texas and should be expected in zone 7a. Indeed, studies at the Army Corps of Engineer's laboratory in Lewisville, Texas, indicate that Salvinia molesta exhibits a greater tolerance to cold temperatures than does water hyacinth (C. Owens, pers. comm.).
Whiteman and Room (1991) stated that Salvinia molesta would persist in areas that experience frost but not the formation of ice on fresh waters. During heavy frosts emergent growth may be killed back, but the submersed stems, insulated by the water, often survive. In the spring, populations may resurge from dormant lateral buds embedded deep in the stems (Lemon and Posluszny 1997).
The coldest winter in 80 years was not enough to freeze out giant salvinia in North Carolina. Stratford Kay and Steve Hoyle, North Carolina State University, discovered Salvinia molesta rampant along the coast in three low-lying regions in September 2000. In January 2001, Hoyle photographed new green leaves developing on frost-damaged plants harbored along the shoreline of golf course ponds in Wilmington. Steve's photographs were made two weeks after low temperatures of 16, 14 and 19° F were successively recorded.
In 1998, a Christmas freeze dropped air temperatures into the mid 20º’s F (-3.8º C) at Toledo Bend Reservoir, Texas. Air temperatures remained below freezing for 10-12 consecutive hours. However, the water temperature did not drop below 50° F (10º C) and floating plants remained unharmed (R. Helton, pers. comm.). By early January 1999, air temperatures were recorded into the upper teens and water temperatures had dropped to 43º F (6.1º C). Regardless of these conditions, plants did not show frost damage and the population rebounded with the return of spring (L. Hartmann, pers. comm.).
Contributor Acknowledgement
References
Authors: C.C. Jacono, M. M. Richerson
Updated: 22 July 2003
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