Iris dichotoma flowers, the Vesper Iris, formerly Pardanthopsis, open ‘religiously’ in the afternoon around 4 pm. By late evening, they are already withered. Nonetheless they are beautiful and it is exciting to watch. It makes you wonder – why the short period of flowering?
According with an article from the Journal of Experimental Botany: “flower opening and closure are traits of a reproductive syndrome, as it allows pollen removal/and or pollination”. Although a peculiar species, the vesper iris is not given as an example in the study.
Those interested can read about the mechanism of opening and closure, carbohydrate metabolism, hormonal regulation and more here – Flower opening and closure: a review, Wouter G. van Doorn, Uulke van Meeteren.
Note on Vesper
In many Christian denominations, vespers is the name used for the evening prayer service. From Greek ‘hespera’ and Latin ‘vesper’ = evening.