Linnaeus also invented a floral clock to tell the time of day. He had observed over a number of years that certain plants constantly opened and closed their flowers at particular times of the day—with the times varying from species to species. Thus, he could deduce the approximate time of day according to which species opened or closed its flowers. Linnaeus planted a garden displaying local flowers, arranged in sequence of flowering throughout the day, that would flower even on cloudy or cold days. He called it a horologium florae or “flower clock.”