The nectar of pale smartweed (Polygonum lapathifolium) flowers attracts Halictid bees, wasps, flies, and occasionally small butterflies. The foliage is eaten by Gastrophysa polygoni (Leaf Beetle sp.), and the caterpillars of the butterflies Lycaena hyllus (Bronze Copper), Lycaena helloides (Purple Copper), and Strymon melinus (Gray Hairstreak). The caterpillars of the latter eats the flowers and seeds. The caterpillars of several species of moths also feed on smartweeds. The seeds of pale smartweed and other wetland smartweeds are a popular source of food to several species of ducks, sparrows, and various other birds. However, because the foliage is somewhat bitter and peppery, this species is not often eaten by mammalian herbivores. Overall, the value of this smartweed species to wildlife is quite high, especially to seed-eating waterfowl.