Amaranthus tuberculatus in bloom

Amaranthus tuberculatus, known in English as "roughfruit amaranth" or "tall waterhemp" (je ne peux pas trouver un nom commun en français), is an annual native to much of eastern and central North America and a few west-coast states. It can reach two metres in height. The spikes of green flowers are not especially showy, but produce abundant seed, making this a useful food source for birds. The glossy foliage is eaten by the larvae of the common sootywing skipper (Pholisora catullus) and some moths.