花钟花对阳光十分敏感。鳞叶龙胆在晴天日照下,蓝紫的朵朵小花盛开,如果将其移入室内,或遮荫处理,5—6分钟之内花朵就会全部闭合,再放在阳光下,花又重新开放。蒲公英和金盏菊的头状花序,在晴天上午7点钟开放,到下午5点就闭合了,如果遇到阴天,整个花序紧闭。睡莲花在太阳升起时开放,太阳落山时花瓣收拢。锦葵科的洋麻,每当清晨花朵便伴着晨曦逐渐开放,要是遮光或提前照光处理,开花时间就会延迟或提早。这些现象说明,植物体内存在着一台决定何时开花的生物钟,它除了具备“在早上开花”这一大体的调节装置外,还受当天具体的光照情况控制,决定开花的确切时间。 Flower clock flower is very sensitive to sunlight. Scale leaf gentian sunshine in the sunny day, blue and purple blossoming flowers in full bloom, if moved into the room, or shading treatment, 5-6 minutes the flowers will be fully closed, and then in the sun, the flowers reopened . The dandelion and calendula flower heads are open on a sunny day at 7 a.m. and closed at 5 a.m., and in the event of a cloudy day, the entire inflorescence is closed. The water lily flower is open when the sun rises, and the petals gather when the sun sets. Malvaceae kenaf, whenever the early morning flowers accompanied by morning gradually open, if shading or early light treatment, flowering time will be delayed or earlier. These phenomena indicate that there is a biological clock in the plant that determines when to flowering. In addition to the general conditioning device “Flowering in the Morning,” it is controlled by the specific light conditions of the day and determines the exact time of flowering.