Desert Four O’Clock, Mirabilis multiflora, is an herbaceous perennial plant, though at higher elevations, it thrives as an annual. It is a member of the Four O’clock Family, Nyctaginaceae. Its other common names are Giant Four O’clock, Showy Four O’clock, and others.
At lower elevations, it is perennial with a splashy show of magenta flowers throughout the summer. As with all desert plants, the flower show depends on available moisture; the more rainfall, the more spectacular the show. At higher elevations, it becomes an annual, producing seeds to perpetuate itself. Even at 4200 ft in elevation in the Mojave Desert, it never survived the winter. The severe drop in temperatures causes it to die back completely, but not before shedding its wonderful seeds. At elevations in which it does not survive the winter, it does a wonderful show in a single season.
It is a low-growing plant that forms a single layer of stems and leaves that sprawl laterally across desert washes, sandy plains, and in piñon-juniper woodlands in slightly higher elevations. It is common in the mountains of East Mojave, in California.¹
Its spreading form can encompass an area six feet across with stems that are thick and succulent-like.
It derives its name from its curious habit of opening its flowers at about 4:00 PM each day, a drought-avoidance adaptation. During the day, its flowers remain tightly closed to escape the harsh desert sun, but open to enjoy the slightly weaker sunlight after 3PM.
Seeds are brown-mahogany, round to oval, and about the size of a pea. When the dried plant is shaken, the seeds will fall to the ground.
¹ Stewart, John M., Mojave Desert Wildflowers: A field guide to the High Desert Wildflowers of California, Nevada, and Arizona, Albuquerque, N.M.: John Stewart Photography, © 1998.