Plant Story–Four o’clocks, Mirabilis; Watch For Them

 Hiking through the grassland, you see a plant with pretty pale flowers. But you can’t match it in the plant book.

It is a four o’clock, genus Mirabilis (Nyctanginaceae, the family of bougainvillea) and the problem is, those white “flowers” are not flowers but bracts that surrounded the base of the flowers. 

The photo is a bit fuzzy, but you can see three dark seeds in the center of the pale bract. 

its not a flower, its a bract around the seeds

I’ve struggled to identify it a number of times.

Mirabilis is a genus of about 60 species, with 21-26 native to the United States. In most states, you can encounter one when hiking.

My pictures above are Mirabilis linearis of the plains and prairies. Its leaves are very narrow and its flowers, when present, are white to pale pink.

More dramatic is Mirabilis nyctaginea, heartleaf four o’clock with bright magenta flowers. 

Here’s another, probably Mirabilis hirsuta hairy four o’clock, though my photo is not close up enough to check for hairs.

A fourth native species is this one, probably Mirabilis oxybaphoides, smooth spreading four o’clock, from middle elevations in the Rocky Mountains. Plant is brown and dry-looking, but flowering profusely.

There are 20 more species in North America. Of the American native four o’clocks, white four o’clock (Mirabilis albida), hairy four o’clock, narrowleaf four o’clock, and the heartleaf four o’clock are found in about 20 states, the others have more limited ranges. (See USDA Plants database). 

The name four o’clock is because the best-known species open their flowers in the afternoon, about 4:00. The floras give pretty much everything in the genus Mirabilis the common name four o’clock but I can’t establish that they all show that pattern of flower opening. (Notice the time when you see one with open flowers). Probably most or all do. Which means, you may pass them by or mis-identify them because the flowers are closed.

They are certainly named because they resemble and are closely related to the four o’clock, Mirabilis jalapa (also called marvel of Peru).  A tropical plant, probably from the Americas, M. jalapa is now found all over the world. It is a major medicinal plant where traditional medicine is practiced. It also became a garden plant, grown as an annual in temperate climates, in Europe in the 1600s. It was introduced to the United States and grown by George Washington and Thomas Jefferson on their estates by the 1780s. It continues to be widely planted. It has escaped and has naturalized in about 25 states. 

four o’clock, Mirabilis jalapa (and this photo was taken at 8:25 am on a cloudy morning; the flowers open about four, stay open all night and, if it is cool, into the morning)

Mirabilis means marvelous. The various species epithets are descriptive: albida means “whitish;” hirsuta means “hairy;” jalapa means from Jalapa, Mexico (whether that is accurate or not is debated); linearis means “linear” or narrow-leafed; oxybaphoides means “resembling Oxybathus” which is another genus in the same plant family; nyctaginea means “like a four o’clock,” referring to the family Nyctaginaceae, which seems circular, except that nyctaginaeus also means “night blooming.”

The bright-colored flowers of four o’clocks, boiled, will dye wool.

The bigger-flowered species are pollinated by hawkmoths. However, four o’clock flowers are often visited by bumblebees and small native bees during the daylight hours when they are open. Then night-flying moths arrive after dark. All of these are at least sometimes effective pollinators. Furthermore, a number of species produce cleistogamous flowers, flowers that do not open and simply self-pollinate, producing reliable seeds. Usually the cleistogamous flowers are at the end of the growing season, ensuring some seed set. In addition to fooling you into thinking the bracts are flowers, four o’clocks’ cleistogamous flowers do not have the bright colors or big stamens of the showy open-pollinated (chasmogamous) flowers shown in the photos in plant books and so don’t fit the photos.

Not only do they feed a variety of pollinators, these plants are hosts to several genera of native butterflies and moths. There are 42 entries in the HOSTS data base of host plants of Lepidoptera, from 14 species in four different families. The native four o’clocks are important supporters of native insects. (And there are two reports of North American insects eating M. jalapa, so although introduced, it is contributing to the food chain.)

Some native wild four o’clocks can be found on disturbed sites, but most are not really weedy. Generally I have encountered them as infrequent plants of fairly open sites, often overlooked if the flowers are not numerous and open. 

These are pretty, interesting, not very common, native wildflowers. Watch for them.

a big stand of heartleaf four o’clock, M. nyctaginea

Comments and corrections welcome.

References

Smith, A. W. 1997. A Gardener’s Handbook of Plant Names. Dover. New York. 

Please take a look at my books. For those who don’t read the internet or prefer books I gathered posts together into actual books, for example:

NoCo Notables, Stories of Common Plants of the Colorado Front Range, Plants have cool stories, about their interactions with other plants and animals and with humans. Go beyond just having a name for the plant, learn more about it. Available from Amazon link or from me. 

 

                                            

And

Look Twice, containing stories of plants from the unique environments found in western Nebraska and eastern Colorado, available from Amazon  link or from me. 

New book coming later this year: Plants You Meet Everywhere. The stories of really cosmopolitan plants such as marigolds, bougainvillea and cheatgrass.