2,100 meters. It occurs in Ilocos Norte , Bontoc, Lepanto, Benguet, Rizal, Zambales, and Laguna Provinces in Luzon. It is also found in India to Southern China . Description: Annual, with large floating stem, rooting at the nodes. Leaves floating, lamina 2.5-7.5 (-10) cm long, 2-8 mm broad, orbicular, cordate at base,