You won't shed a tear when these prickly stems tear your thumbs. They just aren't that fierce. Not that they won't scratch if you're determined to allow it, and if you go into their wetlands. These Persicaria are a little different than the rest of their tribe, with weak clambering stems and round heads. You can find them in bloom in late summer and fall in every state except AK, AZ, CA, HI, ID, MT, NM, NV, UT, WA, and WY, in LB, MB, NB, NF, NS, ON, PE, and QC, and on SPM. Ives Preserve, Lenawee Co MI, 9/17/11. Knotweed family, Polygonaceae.