Q: While on a woods walk I found these black clusters of berries. What are they?
A: They are a fine bird breakfast, but one I wish they wouldn’t eat! The berries are the seeds of the thorny, noxious smilax vine. The glossy green leaves are attractive but it is a miserable weed in your landscape.
I take every opportunity to clip smilax vines to the ground. If I have the energy, I dig up the yellow roots.
This is the only way, other than persistent spraying with glyphosate (click for sources), to eliminate this menace.
I hope you’ll retrace your steps and do any damage to the vine you can accomplish.