Following the movement of the Sun across the sky, the sunflowers grow rapidly, and when it comes time to bloom, they freeze with their "face" to the east. Scientists have shown how useful these abilities are for them to navigate in space.
Children also know about the ability of sunflowers to unfold their flowers following the Sun, from east to west. But even scientists still could not answer the question of whether this movement really brings noticeable benefits to Helianthus annuus. This was demonstrated by simple yet spectacular experiments that Stacey Harmer and her colleagues talk about in Science. Scientists simply tied them, preventing them from turning, or rotated the pots, disrupting the natural course of movement. In both cases, the leaves of the plants turned out to be about 10% less than those of the neighbors, who calmly turned to follow the Sun.
The authors also conducted experiments in a room tightly isolated from external light with artificial lighting, which automatically turned on one or the other sunflower lamp, simulating the movement of the sun. The cycle of this movement did not take 24 hours, but as much as 30 - and the plants could not adapt to this regime. Their turns completely lost consistency and returned to normal only after switching the lighting to a 24-hour cycle. This simple experiment, according to Stacey Harmer et al., Shows that the diurnal movements of sunflowers are regulated not so much by external factors as by internal ones associated with circadian rhythms.
Finally, the sunflower freezes with age. A mature flower no longer turns to the Sun, but nevertheless, it is in a completely definite position, turning to the east. As scientists have shown, this also happens for a reason. Unfolding the pots of plants again, the authors oriented their open flowers to the west, keeping an eye on the number of pollinating insects that both plants visit. It turned out that the flowers turned to the east are pollinated much more intensively: in the cold morning hours, they warm up faster and manage to take five times as many insects.