Swainsona longipilosa

Swainsona longipilosa is an annual plant that typically grows to a height of about 4 cm (1.6 in). Its stems are about 1 mm (0.039 in) wide, densely softly-hairy and ribbed. The leaves are about 20 mm (0.79 in) long with about 5 egg-shaped leaflets with the narrower end towards the base, the side leaflets 5–8 mm (0.20–0.31 in) long and 2–3 mm (0.079–0.118 in) wide with stipules up to 7 mm (0.28 in) long at the base of the petioles. The flowers are arranged in racemes up to 10–50 mm (0.39–1.97 in) long with up to 3 flowers on a peduncle less than 0.5 mm (0.020 in) wide, each flower about 8 mm (0.31 in) long on a pedicel less than 1 mm (0.039 in) long. The sepals are joined at the base, forming a tube about 1 mm (0.039 in) long, the sepal lobes about the three times the length of the tube. The petals are reddish-purple, the standard petal about 6–8 mm (0.24–0.31 in) long and about 7 mm (0.28 in) wide, the wings 5–6 mm (0.20–0.24 in) long, and the keel 8–9 mm (0.31–0.35 in) long and 3–4 mm (0.12–0.16 in) deep.[2] Flowering has been observed in August[3] and the fruit is oblong, about 15 mm (0.59 in) and 3 mm (0.12 in) wide.[2]

Swainsona longipilosa was first formally described in 1993 by Joy Thompson in the journal Telopea from a specimen collected in 1981.[2][4] The specific epithet (longipilosa) means "long hair".[2]

This species of swainsona is only known from two localities in Western Australia where it grows on a stony, exposed hilltop in Acacia woodland in the Carnarvon and Gascoyne bioregions.[2][3]

Swainsona longipilosa is listed as "Priority One" by the Government of Western Australia Department of Biodiversity, Conservation and Attractions,[3] meaning that it is known from only one or a few locations where it is potentially at risk.[5]