The heartleaf four o'clock (Mirabilis nyctaginea) belongs to Nyctaginaceae (the Four-o-clock family). It is a perennial herb that is native to the Midwest and northern Great Plains in the United States. This herb grows in pastures, prairies, roadsides, gardens and wasteplaces, and up to a height of 30-120 cm. The stems are smooth and highly branched, often 4-sided, and sometimes ridged. The leaves are opposite, ovate to cordate, pointed, and smooth on both sides and on the margins, resembling leaves of lilac. The flowers are borne in clusters of 3 to 5 at the ends of branches and bloom from Arpil to November. The flowers lack true petals, and the pink, purple, white or yellowish petal-like structures are actually the upper ends of the sepals. They open for only a few hours and drop, leaving the shaggy-haired developing fruits in the drying, papery cup of bracts.