Kennedia prostrata is a prostrate or twining shrub with wiry stems up to 2 m (6 ft 7 in) long that are hairy when young. The leaves are on a petiole vary from 5 to 50 mm (0.20 to 1.97 in) long, with more or less round leaflets, which are from 6 to 35 mm (0.24 to 1.38 in) long and wide with wavy edges. The end leaflet on a petiolule is from 2 to 9 mm (0.079 to 0.354 in) long, but the side leaflets more or less sessile. There is a heart-shaped stipule about 5 mm (0.20 in) long at the base of the petiole.

The flowers are borne singly or in pairs on a peduncle from 5 to 30 mm (0.20 to 1.18 in) long, with bracts from 2 to 5 mm (0.079 to 0.197 in) long at the base, the individual flowers on pedicels being from 5 to 25 mm (0.20 to 0.98 in) long. The five sepals are hairy, from 6 to 8 mm (0.24 to 0.31 in) in length, and the petals are usually scarlet, rarely white. The standard petal is from 13 to 23 mm (0.51 to 0.91 in) long, the wings from 12 to 18 mm (0.47 to 0.71 in) long, and the keel from 12 to 22 mm (0.47 to 0.87 in) long. Flowering occurs from April to November, and the fruit is a flattened cylindrical pod from 20 to 50 mm (0.79 to 1.97 in) in length.^{[2][3][4][5][6]}

Kennedia prostrata was first formally described by Robert Brown in 1812 in Hortus Kewensis.^[7][8] The specific epithet (prostrata) means "prostrate".^[9]

Running postman occurs in all Australian states and territories, except Queensland and the Northern Territory, and grows in a variety of habitats, often on coastal sand dunes and on rock outcrops.^[1][2][3][5]

The species is naturally adapted to sandy or lighter soils and prefers a sunny position. A widely cultivated species, it grows in temperate to subtropical areas and is hardy in most situations.^[6][10]

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