Scout Info Kentucky IPM Pest Information Pages Pennsylvania Smartweed (Polygonum pensylvanicum) Pennsylvania smartweed is a warm-season annual that can often be found in soybean fields, along ditches and in thickets. This broadleaf weed has narrow cotyledons which are about three quarters of an inch in length with rounded tips. Its narrow, somewhat pointed leaves are alternately arranged on the stem. Stems and leaf petioles are red in color. Pennsylvania smartweed develops an ocrea, or membranous sheath, around the stem at each node. Lady's thumb (Polygonum persicaria) is a similar smartweed species that has hair-like bristles on the edges of the ocrea. At flowering, both species develop a long pinkish spike.

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