Nyctaginaceae: Family

The Nyctaginaceae or Four O'Clock Family contains such famous species as Bougainvillea, Sand Verbena, Umrella Wort and the Four O'Clocks. 

The family can be recognized as herbs (rareily shrubs or trees) with opposite leaves, bracts that mimic sepals, and sepals that mimic petals.  

Scientific Description: 

Hebs (ours), shrubs or trees (tropical).  Leaves opposite, simple, entire, exstipulate.  Flowers generally bisexual, actinomorphic, often with brightly colored bracts subtending them, these often appearing as a calyx, borne in cymes. Calyx of 5 petaloid sepals. Corolla lacking.  Androecium typically of 5 stamesn. Gynoecium unicarpellate, unilocular, the ovary superior.  Fruit an achene, sometimes enclosed by persistent sepals.  The embryo straight or curved.