I recently discovered dense clusters of these “berries” in an old field near Clayton Michigan. I didn’t know what they were at first and had to do some research. It turns out these aren’t berries, they’re rose hips. Specifically, they’re the hips of a multiflora rose (Rosa multiflora, Rosaceae).
The compound leaves have five to eleven leaflets and feathered stipules, seen above. The shoots are leggy and arching, something like a cross between a vine and a shrub. They’re also adorned in relatively sparse yet large recurved thorns.
When I realized this was a rose, I wondered how I managed to overlook the showy flowers a few months ago. It turns out I didn’t, I just didn’t know what I was looking at back then. I looked through my photo collection from the summer and found that I took this photo of a flower back in July:
Although this is an interesting plant with showy flowers in the summer and attractive fruit in the fall, apparently it’s an introduced species that is highly invasive. Many states list it as a prohibited or noxious weed.