Seasonal Growth of Waterhyacinth in the Sacramento/San Joaquin Delta, California
2005
Spencer, D.F. | Ksander, G.G.
Waterhyacinth (Eichhornia crassipes (Mart.) Solms), is a serious problem in the Sacramento/San Joaquin Delta, California. There is little published information on its phenology or seasonal growth in this system. Waterhyacinths were sampled at 2 to 3 week intervals from November, 1995 to July, 1997 and the following measurements were made on individual plants: dry weight, height, number of living leaves, number of dead leaves, and the width of the largest lamina. Lamina area per plant was estimated by multiplying the number of living leaves by the mean lamina area for each sampling date. We also noted the presence or absence of flowers. Height and dry weight increased from less than 10 cm in winter and early spring to more than 80 cm in late summer and from 10 g to 85 g, respectively. Number of dead leaves was greatest in the winter and declined through June. New leaves started to appear in March. Starting in March, lamina area per plant increased through October. Plants with flowers were present at the sample site from May 20 to August 12 but not abundant. A logistic regression equation relating relative lamina area per plant to accumulated degree-days was developed. Maximum growth was achieved in October, later than previously reported for waterhyacinth in southeast U.S. populations.
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