Nyctinasty in Cacti

July 15, 2015

Nyctinasty in cacti plants 2015

: Menashe Davidson
Summary AuthorMenashe Davidson
This photo composite shows nyctinasty in a type of hedgehog cactus. Times are on the upper left of each photo. In botany, a nastic movement is a non-directional response, such as the closing of the petals on a flower at night. Similar to most flowering plants, most cacti flowers respond to sunlight or lack of it by opening (during daylight to intercept sunlight) and folding (at night).  These movements are controlled by circadian rhythms, a process that displays a built in (endogenous) oscillation of approximately 24 hours. Note that the flowers are wide open near midday (upper right) but closed in the morning and evening (upper left and lower right).
Because the desert environment where most cacti thrive is so barren and because cactus plants are rather stark in appearance, when they're in bloom their flowers are particularly noticeable. Photo composite taken from the garden terrace of my apartment on April 16 and 17, 2015.