Abstract (eng)
Numerous cases of movements are documented in plants. Plant movements irrespective of a stimulus and with a direction determined by the morphology are called nasties. They are distinguished from tropisms, which are stimulated by an external impulse, such as light or gravitation by the virtue of the fact that the organs of the plant follow the origin of the stimulus. A rhythmic motion regulated by internal processes, an autonomic movement, is known as circadian rhythmic.
The flowers of Bulbophyllum lobbii and its relatives show a periodic movement, which is regulated by an endogenous, circadian rhythm of 24 hours. The intensity of the movement always decreases with increasing senescence of the flower. In all Bulbophyllum lobbii plants investigated, the rhythm of the flower movement continued under constant light or darkness, but was much affected by changes from light to darkness or vice versa, which elucidates the high dependence of this particular circadian rhythm on the exogenous factor light. Temperature has no direct influence on the rhythm of the flower movement. High temperature has negative effects on its intensity.