This is a circumpolar species, here occurring in deciduous forests and thickets, especially in disturbed areas, but also sometimes in more open weedy settings. Presumably native, but apparently spreading northward in Michigan in recent years. There are very few pre-1900 collections, all from the southern Lower Peninsula (except for an 1890 O. A. Farwell collection with minimal data from Keweenaw Co. which is suspect and not mapped) and none before 1879 (Kent Co.). There seems to have been rapid spread starting in the 1940’s.

The bristles on the fruit are hooked at the tips and thus it is easily dispersed on fur, feathers, and human clothing. The stems are sometimes rather smooth, with a good lens (or sensitive fingers) needed to be sure of the retrorse barbs on some internodes. The greater roughness of the upper surface of the leaves, as well as the retrorse (or at least spreading) barbs on the margins, are generally good distinctions from G. triflorum, also common in deciduous forests.

This annual typically germinates in the fall, and young plants with large cotyledons and the first whorls of leaves are visible after leaf fall in forests. This is presumably a useful strategy for maximizing photosynthesis during the light window in forests when the canopy is bare, and may also aid in growing through leaf litter by starting growth before the litter is consolidated into a denser layer by snow and rain.