The four o'clock flower is a botanical rebel that defies standard genetic rules.

Nature · Published 3 October 2026 Swipe more like this →

In short: Known as the marvel of Peru, this plant blooms in the late afternoon, filling the night with fragrance. Beyond its nocturnal habits, it is a genetic outlier that challenged early theories of inheritance and continues to surprise scientists with its ability to display multiple colors on a single stem.

Mirabilis jalapa, or the four o'clock flower, is a perennial native to the Americas that earned its common name by opening its funnel-shaped flowers between 4 and 8 o'clock in the evening. These blossoms, which are actually pigmented modifications of the calyx rather than true petals, remain open for 16 to 20 hours. They are specifically adapted to attract nocturnal pollinators like sphinx moths with a scent reminiscent of tobacco flowers.

The plant is a historical heavyweight in genetics. Around 1900, Carl Correns used its variegated leaves to demonstrate cytoplasmic inheritance, proving that certain traits are passed down outside the cell nucleus. It also provided a clear example of incomplete dominance; when dark-pink and white-flowered plants are crossed, the offspring produce light-pink flowers, a result that initially appeared to contradict Mendelian laws but ultimately reinforced them.

Beyond genetics, the plant is a biological multitasker. It contains a variety of chemical compounds, including rotenoids in its roots and betaxanthins in its flowers, which have shown antimicrobial activity against Candida albicans and potential as efflux pump inhibitors against drug-resistant bacteria. It is also used in bioremediation to clean soils contaminated with heavy metals like cadmium. Despite its utility—ranging from food coloring to traditional medicine—the seeds are considered poisonous, and the plant can become an aggressive, self-seeding weed in tropical environments.

The plant's name reflects its complex history. While Linnaeus named it in 1753, the epithet 'jalapa' likely refers to the Mexican city of Xalapa, which was historically associated with a purgative drug. Today, the plant is celebrated globally under various names, from 'night beauty' in Bulgaria to 'evening gem' in West Bengal, serving as both an ornamental garden staple and a subject of ongoing scientific inquiry.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• Beyond the garden: the surprising history and hidden chemistry of the morning glory
• The world's most famous tropical flower is actually a man-made Polynesian invention
• Why these fleeting blue flowers are named after a pair of Dutch botanists
• Why your garden should bloom after dark to attract hidden nocturnal visitors
• Why this delicate garden flower is better known as horny goat weed
• Is a mirror the only way to see the self?
• The hidden bureaucracy of owning a 'tiny' pet pig
• The Mississippi Delta is not a delta, but a fertile, historically complex alluvial plain.
• How a chemical factory in Japan turned a quiet fishing port into a tragedy
• Mistletoe is not just a holiday decoration but a sophisticated, often lethal, plant parasite.
• Nature's greatest con artists use deception to survive, but how does mimicry actually work?
• Eight-legged worlds smaller than a millimetre, not one clade

More in Organisms · More in Nature · Latest · A–Z · All topics