Germination characteristics of Zannichellia palustris from a northern California spring-fed river

•Light and temperature affected Zannichellia palustris germination.•Photoperiod and light intensity have no effect above stimulatory light levels.•Germination is temperature-dependent above stimulatory light levels.•Maximum germination rate and fraction was between 25 and 30°C.•Germination time was log-normally distributed across the seed population.