When I was young, I lived in Scotland with my parents. I had a good time there.
One morning, I ran to the garden, and said to the old Scotsman who worked there. "Today I am going up the mountain for berries."
"No, no, Missey, not today." he said, "It will rain."
"No, it will not rain." I said, "The sun is up. The cook says it will be fine. The glass in the hall does not say rain."
"Tuts, tuts." said the old man, "I care for no suns, or cooks, or glasses. The pimpernel (海绿) says it will rain, and so it will rain. Flowers, Missey, always tell the truth. When they say rain, go and get your umbrella."
Sure enough, by noon the rain was pouring down. After that, I looked with great respect at the tiny flower, sometimes brickred, sometimes blue, which could tell about the weather. But the pimpernel is not the only plant that is a weather prophet.
If you go into the garden, and find the African marigolds shut after seven o'clock in the morning, you may be pretty sure that there will be a rainy day. There is a little single marigold which shuts up in a hurry if the sky becomes clouded. It is called the "rainy-marigold".
Most plants which we call "weather prophets" shut up for rain. But some plants open for rain. The cause of the opening and closing is probably the difference in light. Most likely these plants shut their flowers because there is too little light.
But you know there are some plants which become smaller in a strong light and love the shade. You will find that most shade-loving plants, as the verbenas, do not close for rain.
Lilies, tulips and other flowers that love the sun shut for rain. Tulips are careful not to open their cups very wide in the morning if it is likely to rain. The roses make no change. They seem not to fear wet.
On the whole, you may be pretty sure, if you go into your garden, and find many flowers as tulips, marigolds and morning glories shut, it will be a stormy day, unfit for picnics or long walks.