PLANTS WITH A SENSE OF TIME
Plants with a rather hard-and-fast sense of time are another phenomenon. The great botanist Linnaeus is said to have de­vised a clock composed of flowers that opened at set hours so that he could tell the time of day by it.

No complete agreement exists among modern observers as to the precise opening times of various flowers. There are bound to be discrepancies in any schedule due to slight differ­ences in sunrise time within any given time zone. Also time of year, cloudy weather, and location of flowers in one's own garden all affect the time of opening. However, it is still true that certain flowers do have widely varying times for opening up, and that these times range from pre-dawn to late at night.

No child could expect to plant a whole flower-clock, but he could try out a few of them-say a late-morning riser like portulaca, a sleepy-head like four-o'clocks, and a night-owl like the moonflower.

The following list is presented as approximately correct. It will be most accurate on sunny days and when plants are grown in full sun.

The prayer plant (Maranta kerchoveana) is a house plant that also has an infallible time-sense. All day long the leaves are held at right angles to the stem. At nightfall they move slowly, but visibly, until they are pointing upward, lying close along the stem and suggesting hands in an attitude of prayer. They are like this at bedtime, but in the morning have resumed their daytime horizontal position.