A curious aspect of M. jalapa is that flowers with different colours grow simultaneously on the same plant.
Additionally, an individual flower can be splashed with different colours. Flower patterns are referred to as sectors (whole sections of flower), flakes (stripes of varying length), and spots. A single flower can be plain yellow, pink or white, or have a combination of sectors, flakes and spots. Furthermore, different combinations of flowers and patterns can occur on different flowers of the same plant. Another interesting point is a colour-changing phenomenon. For example, in the yellow variety, as the plant matures, it can display flowers that gradually change to a dark pink colour. Similarly white flowers can change to light violet.
The flowers usually open from late afternoon (around 4'o clock) onwards, hence the first of its common names. Flowers then produce a strong, sweet-smelling fragrance throughout the night, then close for good in the morning. New flowers open the following day.
Despite their appearance, the flowers are not formed from petals – rather they are a pigmented modification of the calyx. Similarly, the 'calyx' is an involucre of bracts.
The flowers are pollinated by long-tongued moths of the Sphingidae family, such as the sphinx moths or hawk moths and other nocturnal pollinators attracted by the fragrance.
Mirabilis jalapa hails from tropical South America, but has become naturalised throughout tropical and warm temperate regions. In cooler temperate regions, it will die back with the first frosts, regrowing in the following spring from the tuberous roots. The plant does best in full sun. It grows to approximately 0.9 m in height. The single-seeded fruits are spherical, wrinkled and black upon maturity (see picture), having started out greenish-yellow. The plant will self-seed, often spreading rapidly if left unchecked in a garden. Some gardeners recommend that the seeds should be soaked before planting, but this is not totally necessary. In North America, the plant perennializes in warm, coastal environments, particularly in USDA Zones 9–10. The fragrance of the flower is more intense and noticeable during the warm period of the day. Usually, the flowers are found in yellow, pink and white colors but you can find different combination of flowers growing on the same single four O’ clock plant!
Around 1900, Carl Correns used Mirabilis as a model organism for his studies on cytoplasmic inheritance. He used the plant's variegated leaves to prove that certain factors outside the nucleus affected phenotype in a way not explained by Mendel's theories. Correns proposed that leaf colour in Mirabilis was passed on via a uni-parental mode of inheritance.
Also, when red-flowered plants are crossed with white-flowered plants, pink-flowered offspring, not red, are produced. This is seen as an exception to Mendel's Law of Dominance, because in this case the red and white genes are of equal strength, so neither completely dominates the other. The phenomenon is known as incomplete dominance.
Eight betaxanthins (indicaxanthin, vulgaxanthin-I, miraxanthin-I, -II, -III, -IV, V and -VI) can be isolated from M. jalapa flowers.
Rotenoids (mirabijalone A, B, C and D, 9-O-methyl-4-hydroxyboeravinone B, boeravinone C and F, and 1,2,3,4-tetrahydro-1-methylisoquinoline-7,8-diol) can be isolated from the roots.
A fatty acid (8-hydroxyoctadeca-cis-11,14-dienoic acid) is found as a minor component in the seed oil.
Analysis of the methanolic extract of the aerial parts yields β-sitosterol, stigmasterol, ursolic acid, oleanolic acid and brassicasterol.
Bioassay-guided fractionation of an organic extract of the cell mass from a manipulated plant cell culture of M. jalapa led to the isolation and subsequent identification of an isoflavone, a roteinoid and a dehydrorotenoid, Two of these compounds are responsible for the antimicrobial activity against Candida albicans.
Bioassay-guided fractionation of the methanolic extract of M. jalapa also led to the isolation of an active polyphenolic amide: N-trans-feruloyl 4′-O-methyldopamine. This compound shows moderate activity as an efflux pump inhibitor against multidrug-resistant Staphylococcus aureus.
The flowers are used in food colouring. The leaves may be eaten cooked as well, but only as an emergency food.
An edible crimson dye is obtained from the flowers to colour cakes and jellies.
In herbal medicine, parts of the plant may be used as a diuretic, purgative, and for vulnerary (wound healing) purposes. The root is believed an aphrodisiac as well as diuretic and purgative. It is used in the treatment of dropsy.
The leaves are used to reduce inflammation. A decoction of them (mashing and boiling) is used to treat abscesses. Leaf juice may be used to treat wounds.
Powdered, the seed of some varieties is used as a cosmetic and a dye. The seeds are considered poisonous.
The plant has a potential for the bioremediation of soils polluted with moderate concentrations of heavy metals such as cadmium.In Bangladesh it is called sandhyamalati (Bengali: সন্ধ্যামালতী), meaning "evening flower".
In Pakistan it is called gul adnan (Urdu: گل عدنان) or gul-e-abbas (Urdu: گل عباس).
In Sri Lanka it is called hendirikka (Sinhalese: හෙන්දිරික්කා).
In Karnataka it is called sanje mallige (Kannada: ಸಂಜೆ ಮಲ್ಲಿಗೆ).
In Tamil Nadu it is called andhi mandhaarai (Tamil: அந்தி மந்தாரை).
In Thailand it is called bānyĕn (Thai: บานเย็น), meaning "evening blossom".
In Andhra Pradesh it is called chandrakantha indraganti (Telugu: చంద్రకాంత ఇంద్రగంటి).
In Bulgaria it is called noshna krasavica (Bulgarian: ношна красавица), which means "night beauty", "night belle".
In Germany it is called Wunderblume, which means "flower of miracle".
In Kerala it is called naalumani poovu (Malayalam: നാലുമണിപ്പൂ, പതിറ്റടിമുല്ല).
In Maharashtra it is called gulabakshi (Marathi: गुलबक्षी).
In Assam it is called godhuli gopal (Assamese: গধূলিগোপাল), godhuli meaning "evening".
In Maithili it is called sanjhaa phool as it blooms in evening.
In Orissa it is called rangani.
In Punjabi it is called sham di sohnap, which means "evening beauty".
In Indonesia it is called bunga pukul empat.
In China it is called the "shower flower" (Chinese: 洗澡花; pinyin: xǐzǎo huā) or "rice boiling flower" (simplified Chinese: 煮饭花; traditional Chinese: 煮飯花; pinyin: zhǔfàn huā) because it is in bloom at the time of these activities.
In Hong Kong it is known as "purple jasmine" (Chinese: 紫茉莉; pinyin: zǐ mòlì).
The Turkish name is akşam sefası, which means "evening pleasure".
In the Netherlands and in France the name of the plant is nachtschone and belle de nuit respectively meaning "beauty of the night".
In Italy it is called bella di notte, which means "beautiful during night".
In Iran it is called laleh abbasi (Persian: لاله عباسی).
In Japan it is called oshiroi-bana (Japanese: オシロイバナ), as the white, powdery endosperm inside of mature seeds looks like oshiroi, the powder foundation used by geishas.
In Israel it is named lilanit rav-gonit (Hebrew: לילנית רב-גונית), and more commonly called malkat halayla (Hebrew: מלכת הלילה), meaning "queen of the night".
In Namibia it is called vieruurtjie ("four o'clock") as it starts to open at 16:00 until the morning.
In Slovenia it is called nočna frajlica, meaning "night missy".
In Serbia it is called noćurak (Serbian: ноћурак), sometimes noćna frajla (Serbian: ноћна фрајла).
In Romania it is called frumoasa nopții, meaning "the beauty of the night", or also noptiță.
In the Philippines it is called prinsesa ng gabi, meaning "princess of the night" or sometimes alas quatro, "at four o'clock".
In Chile it is called putita, meaning "little hooker", because she is prettiest when her flowers come out at night.
In Mexico it is called maravilla, meaning "marvel".
In Malta it is called ħummejr.
In Russia it is called zor'ka (Russian: зорька), meaning "dawning".
In Syria it is called alshab alzarif (Arabic: الشاب الظريف).