Question

Why mirabilis jalapa is called 4 o'clock plant?

Answer 1

The plant is called four-o’clock because its flowers, from white and yellow to shades of pink and red, sometimes streaked and mottled, open in late afternoon (and close by morning).

Answer 2

The common name of four o'clocks was given to Mirabilis jalapa because the flowers of this plant do not open until late in the day.