Mirabilis nyctaginea is a perennial herb from a large taproot to 7 cm wide, stems coarse, to 1.5 m tall, smooth, gray-green, nodes swollen, stem repeatedly forked.
Leaves opposite, stalks 1-3 cm long, blade to 3-10 cm long,to 7 cm wide (Yatskievych 2006), egg to heart-shaped, tip pointed, base lobed or truncate (similar to those of lilac).
Flowers pinkish, petals, calyx corolla-like tubular,1 cm long, radially symmetrical,bell-shaped, calyx lobes 5, notched at tip, tube wrapped tightly around ovary, in clusters of 3-5 in a saucer-like, 5-lobed hairy, reddish floral bract ca 2 cm wide; inflorescence of terminal tufts of flower clusters; flowers open in late afternoon, close by morning, most are pollinated by nocturnal insects, pollinated flowers close by 7:30 AM, unpollinated flowers remain open until 11:00 AM and are pollinated by bees and other morning insect visitors; flowers blooming late in season are smaller, stay closed and are self-pollinating; blooms June-Sept. (WeedScience 2002).
Fruit dry, gray-brown, cylindrical 1-seeded achene, 0.4-0.5 cm long, bluntly 5-ribbed, tapered at both ends, surface densely warty between ridges, and covered with long shaggy hairs, becoming gelatinous and sticky when wet; achenes in clusters cupped within subtending 0.8-1.5 cm tall floral bract; apparently falling near parent plant, not otherwise dispersed (WeedScience 2002; The Plants Project 2006).
Wetland status: FACU-.
Frequency in NYC: Infrequent.
Origin: Western North America.
Habitat: Open dry soil, roadsides, fill.
Notes: Listed as a noxious weed in some states (Flora of North America 1993+).