Comparative Growth of Giant Reed (Arundo donax L.) from Florida, Texas, and California

Giant reed (Arundo donax L.) occurs throughout the U.S. from California to Maryland. It is considered an invasive plant in some parts of this range but not others. To test the hypothesis that plants from different regions have similar growth characteristics, we grew plants from stem cuttings collected at two sites in Florida, one site in Texas, and two sites in California in a common garden experiment in Davis, California. Pants were grown outdoors in topsoil or a 90:10 sand:topsoil mix, in large plastic containers. All plants survived winter conditions in Davis, California, during 2004, when the minimum air temperature was -3.3 C. Stem width, number of stems per plant, number of leaves per stem, total leaf area per plant, and RGR sub(NSTEMS) did not differ among the provenances studied. Variegated plants had somewhat greater stem angles, indicating that the stems were more prostrate early in the growing season. Differences in stem height, number of in ternodes per stem, and mean internode distance were consistent with those expected from the inclusion of variegated plants in this study. Plant dry weight differed depending on plant origin and substrate type. Variegated plants weighed less regardless of the substrate. With the exception of a variegated form, plants from disparate geographic locations grew equally well under similar conditions, and no differences in growth characteristics were found that would suggest different invasive potential and impact on resident species.