Polygonaceae is a family of plants which include the smartweeds, knotweeds, buckwheats and dock. Look for the swollen "joints" or sheathes where the leaf is attached. The stems often zig-zag and their clustered flowers look rather bead-like, consisting of sepals, not petals.
Two members of this family garnered my scrutiny during the OOS Conference. Samples taken from a Wayne County wetland allowed for a close inspection of the non-native Curly Dock, Rumex crispis and the wetland native Water Dock, Rumex orbiculatus. Curly Dock, recognized by its curly leaf, is featured in this photo from Big Island Wildlife Area, a wetlands near Marion, Ohio. Also growing there is the straight leafed Water Dock, a robust wetland plant having stems tinged with pink.
You might also note those 2 jointed "stalks" with pinkish hue, attached to the black and white bird. That is a little bonus thrown in with today's botany: one of the three Black-necked Stilts found feeding in Marion County wetlands. A very rare visitor to Ohio, probably less than 20 B-N Stilts have been seen in all of Ohio since the turn of the century. It is a good thing I was out photographing wetland plants! :)