Plebejus argyrognomon, common name Reverdin's blue is a butterfly of the family Lycaenidae.

[2] These butterflies inhabit grassy flowery places at an elevation of 200–1,500 metres (660–4,920 ft) above sea level.

The upperside of the wings is violet-blue in males, with a narrow, black border and a white fringe, while in the females it is dark brown, with black bordered orange lunules at the outer edge, especially visible on the hindwings.

Caterpillars are pale green with orange brown longitudinal stripes, up to 20 millimeters long.

The larvae feed on Coronilla varia, Securigera varia, Trifolium repens, Melilotus officinalis, Medicago sativa, Lotus corniculatus, Onobrychis viciifolia, Vicia sativa and Astragalus glycyphyllos.