A monoecious population of Hydrilla verticillata (L.f.) Royle, occurri
ng in the Wazirabad reservoir on the river Yamuna at New Delhi, produc
es seeds profusely during late winter. The seeds are light sensitive a
nd germinate within a week at laboratory temperature (23-28-degrees-C)
. Seeds stored dry or in water in darkness for up to 1 year germinate
readily in light. Thus, seeds offer a long-term strategy for survival
of Hydrilla after prolonged dry periods in regions with a monsoon clim
ate.