How do plants know the seasons, and what came first, rain or the seas?
H ow do plants know what the seasons are? Every plant has a biological clock that responds to temperature and light. With bulbs, small miniature plants with flowers develop within the bulb during the previous season (or in autumn, for spring blossoms). Each type of flower is programmed to start growing a specified number of months after the formation of this miniature plant (for example, tulips wait five months). After this wait, the bulb begins to let water enter the cells of the miniature plant. This makes the cells swell and elongate, so the flower, stem and leaves grow bigger until they are fully grown. After the stem begins to grow, the growth rate depends on the temperature. If the weather is warm, the plant will grow faster and will bloom earlier.