The Caryophyllidae
Family Overview - The Caryophyllales
Nyctaginaceae - the Four O'Clock Family

Diversity:  A small (30 genera, ca. 300 species), but distinctive family of often Summer-blooming herbs, shrubs and trees that tend to produce fairly large, showy, incomplete flowers.  The ethnoflora includes one food crop, the mauka (Mirabilis extensa), a root vegetable of minor local importance in the South American highlands. Garden Four-O'Clocks Mirabilis jalapa species are grown as ornamental plants, as are species of Bougainvillea and Abronia are commonly cultivated in warmer regions.

Distribution:  Found throughout the World - cosmopolitan - but centered in north-temperate areas.  Texas with 13 genera and 55 species; and one, Abronia macrocarpa, listed as endangered. (Texas list)

Floral structure: 

Significant features:  The leaves are simple, entire, estipulate, and usually opposite. The flowers are usually bisexual, have a 3-8-lobed uniseriate perianth of connate, petaloid sepals and are subtended by bracts that range in appearance from large and brightly colored to reduced and calyx-like.  The androecium consists of 1 (usually = calyx lobes = 5)-30 hypogynous, commonly unequal stamens that may be either free or monadelphous. The gynoecium is a single simple pistil with a superior ovary containing one locule and one basal ovule. The fruit is an achene that is often enveloped by the persistent base of the androperianth, mostly calyx tube.  Thus, the true fruit (mature ovary), which is often an achene, is enclosed by an outer layer that is often modified as a dispersal aid.  This pome-like combination of perianth and gynoecium is known as an anthocarp.


Abronia macrocarpa - 'Large-fruited sand-verbena' inflorescence 
Mirabilis jalapa - pink synsepalous calyx (left) subtended by green bracts at anthesis.  These reflex (right) at maturity to reveal the anthocarp

   Bougainvillea sp. - flower with white synsepalous calyx subtended by pink bracts

More information on the Nyctaginaceae

Return to the Biology 301 homepage, or the Caryophyllidae page
19 Feb 2010