An interesting fact when observing flowering vegetation is the synchronization of the opening and closing of buds with daylight. But quite exotic daylilies, hibiscus, as well as other exotic plants, which are not so common, also have this quality.
Scientists have more than one version about why flowers close at night or in inclement weather. It should be immediately clarified that each of the theories has its own supporters and the foundation of scientific observations that determine the right to life.
Versions and theories of the reasons for closing flowers at night
Pollen protection against dew. The reason for this explanation is that with too much moisture, pollen literally cementes and pollinating insects can no longer tolerate it in order to pollinate other flowers and plants of this species.
Flowers close at night to create an obstacle to the insects, which often strive to spend the night in the "embrace" of the flower, to penetrate the core. But insects also learned to cheat flowers - many penetrate the flower at the time of incomplete closure of the flower and successfully spend the night in inflorescences in comfort.
Charles Darwin believed that closing flowers at night is associated with protective mechanisms against nighttime temperature drops, which can be too significant in amplitude and can provoke the death of a tender pistil and stamens.
Another fairly exotic theory is the assumptionthat the flowers close at night because of the “fear” of being damaged by nocturnal animals and insects, in which the period of activity just falls in the dark.
Interesting fact: This statement is often criticized by nerds, but for example, deer and hares very much like to eat flowering herbs at night to protect themselves from daytime predators. Perhaps the mechanism for closing the inflorescences is associated with the masking of flowers, so as not to be too noticeable. By the way, many species of small owls literally "graze" on inflorescences at night in search of insects, which can make up the vast majority of their diet in the warm period of the plants blooming, insects that fly to eat nectar.
How do flowers trigger a night-time closing mechanism?
In addition to the fact of closing on inflorescences at night, which is very similar to imitation of sleep, the mechanism that allows the plant to "observe the sun" is also interesting. Although they do not have such organs of vision as birds and animals, there are dorsoventral organs. Under the influence of external factors, among which heat, light and moisture stand out, plants are able to perform nasal movements. Triggers for infusions are changes in the tissues of plants, the amount of chlorine and calcium.
A good example that causes nastia (movement) to open during the day and close in the evening is the “behavior” of a white water lily. Water lilies always reveal inflorescences in the daily segment of the daily rhythm, and at sunset close together.Therefore, the most important factor advocating for closing inflorescences at night is photonasty - a reaction to the level of illumination.
As a result, plants close at night, primarily due to the presence of photosensitive cells in plants that can participate in positive photonasty. Accordingly, theories about the effects of light and the values of the level of illumination have the most prevailing scientific justification in the question of why some flowers close at night.
