Fruits and seeds of the genus Chenopodium have been considered taxonomically important but have not been fully studied or utilized. We discuss the importance of describing fruit and seed morphology at low magnification to improve the identification and taxonomy of North American taxa of Chenopodium, which in a large part remains unresolved. A new species, Chenopodium nitens Benet-Pierce & M. G. Simpson, is described, integrating these reproductive characters with general vegetative characters.