Grewell, Brenda J. , Canington, Deborah , Futrell, Caryn J. .
Growth and morphological responses of invasive Ludwigia peploides ssp. montevidensis to a water depth gradient.
LUDWIGIA peploides (Kunth) Raven ssp. montevidensis (Spreng.) Raven (floating primrose-willow) is a South American perennial herb that is aggressively invading wetland and riparian habitats in California. This creeping emergent weed rapidly forms dense floating mats that displace native vegetation and open water habitat, and reduce effective control of West Nile Virus mosquito vectors. A leading hypothesis is that the invasive spread of L. p. montevidensis may be due to recent hydrologic changes in invaded wetlands. Development of effective management strategies to control invasive Ludwigia populations requires information regarding weed tolerance and response to a range of environmental conditions. To inform water managers, we compared growth, morphological and anatomical responses of rooted cuttings across a water depth gradient in aquatic mesocosm experiments. Shoot length, number of rooting nodes and branches, leaf area, relative growth rate and total plant biomass decreased with increasing water depth. Plants at one meter depth had the highest leaf mass ratio, and there were no difference in specific leaf area among treatments. Floating root:shoot ratio was highest in shallow and medium water depths, and plants at 0.5 meter depth produced the most upward growing gas-filled roots. Plants in water up to 0.5 meters deep produced extensive aerenchyma from a stem phellogen, while aerenchyma of upward growing roots expands from the cortex. At one meter depth, plants were not able to develop significant aerenchyma tissue as an adaptation to anoxia. Results indicate that restoration of deep water habitat may suppress the growth of invasive Ludwigia in California.
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1 - USDA-ARS Exotic & Invasive Weeds Research, Department of Plant Sciences MS-4, University of California, Davis, 1 Shields Avenue, Davis, California, 95616, USA
2 - University of California Davis, Section of Plant Biology, One Shields Avenue, Davis, California, 95616-8537, USA
3 - USDA-ARS Exotic & Invasive Weeds Research, Aquatic Weed Laboratory, University of California, Davis, Levee Road, Davis, California, 95616, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 4:30 PM