Polygonum delopyrum (synonym Polygonella ciliata), the fringed jointweed or hairy jointweed, is a plant species endemic to Florida. It is found in pinelands and sandy pine barrens at elevations less than 50 m, in central and southern parts of the state.

Polygonum delopyrum is an annual herb up to 110 cm tall, branching above the base. Leaves are narrow and linear, up to 5 cm long, with cilia (long flexible hairs) along the margins. Inflorescence is up to 45 mm long. Flowers are white, some hermaphroditic (male and female together) but others pistillate (female only). Achenes are brown, triangular in cross-section, up to 4 mm long.