What do you know about flower clocks?

Long ago, people noticed that flowers open at different times: some in the morning, others in the evening, and others only at night. For example, dandelions open at 5 am, and by 2 or 3 pm they close. Water lilies open their snow-white petals at 7 a.m. and turn to follow the sun throughout the day.
The Swedish scientist Karl Linnaeus has observed plants for many years and found out when flowers of different plants open and close. In his garden, the scientist made a flower clock. In a round flowerbed grew chicory and rose hips, dandelions and potatoes, marigolds and other plants. Karl Linnaeus could tell the time by seeing which flowers were revealed.
In many cities of the world there are flower clocks, but the time on them is shown by hands with a mechanism hidden in the ground. Flowers are just a beautiful decoration of the clockwork.