Production and survivorship of the functional stolons of giant cutgrass, Zizaniopsis miliacea (Poaceae)

Giant cutgrass [Zizaniopsis miliacea], a tall emergent grass native to the southeastern United States, was studied in two Florida lakes. In Lake Semin ole (15176 ha) giant cutgrass forms large expanding stands, but in Lake Ali ce (9 ha) it IS confined to a stable narrow fringe. By monitoring individua l plants in Lake Seminole, it was found that an average decumbent flowering stem produced three flowers and ten nodes, 80% of which became rooted in t he substrate. Such flowering stem development could potentially result in s tand expansion of 2.2-2.7 m/yr, depending upon water levels and rates of no de rooting. Once flowering stems became decumbent in Lake Alice, they typic ally broke, producing no more than two flowers with four nodes in a growing season. While still attached to the parent plant, few of these nodes were able to become rooted in the substrate, limiting the rate of stand expansio n in Lake Alice. Sections of flowering stems bearing axillary shoots that w ere detached from the parent plant and free-floating could become rooted on reaching shallow water and produce robust, new, flowering plants. This int eresting mode of population dispersal and spread has important implications for the distribution and management of giant cutgrass.