Leaf expansion rate and life span of floating leaves in Victoria amazonica (Poepp.) Sowerby growing in Kebun Raya, Bogor, Indonesia.

Abstract

We investigated the growth and life span of floating leaves in Victoria amazonica (Poepp.) Sowerby, growing in a shallow pond of the Bogor Botanical Gardens, West Java, Indonesia. In the pond, five plants were selected and the diameter of each leaf was measured at two-day intervals for two weeks to detect the fate of each individual leaf. A visual inspection of any lost (decayed) areas was also conducted at each observation date to evaluate the percentage of decayed leaf area. Leaf life span was estimated from the time interval for the emergence of new leaves, provided that the number of leaves per plant was constant. It was shown that the maximum value in leaf diameter was 2.35 m (4.34 m² in area) with a mean value of 1.6-1.7 m. Each plant was composed of 10-15 floating leaves and while the total leaf area per plant differed considerably (minimum value 12.1-17.2 m², maximum value 27.6-31.2 m²), the minimum and maximum values in time interval for new leaf emergence and in leaf life span were quite similar (2.78 and 2.88 days and 30.8 and 39.7 days, respectively) among the five plants observed. Specific leaf weight (mg·cm^-2) was 7-9 for young leaves and 10-12 for mature leaves, respectively.