Thomasia dielsii

Thomasia dielsii is an erect to spreading shrub that typically grows to 0.2–0.4 m (7.9 in – 1 ft 3.7 in) high, 0.8–1 m (2 ft 7 in – 3 ft 3 in) wide and has its young stems covered in greyish, star-shaped. The leaves are egg-shaped to oblong, 15–25 mm (0.59–0.98 in) long and 6–7 mm (0.24–0.28 in) wide on a petiole 4–5 mm (0.16–0.20 in) long. The edges of the leaves are wavy and slightly serrated, the upper surface with a few star-shaped hairs, the lower surface more densely hairy. There are hairy, smaller leaf-like stipules at the base of the petioles. The flowers are arranged in racemes of 4 to 9, each flower on a hairy pedicel 5–7 mm (0.20–0.28 in) long, with hairy, linear bracteoles about 6 mm (0.24 in) long at the base. The sepals are purple, violet and blue, 9–10 mm (0.35–0.39 in) long, and there are no petals, the style protruding above the stamens.[2][3]

Thomasia dielsii was first formally described in 1904 by Ernst Georg Pritzel in Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie from specimens he collected near Cranbrook.[4][5] The specific epithet (dielsii) honours Ludwig Diels.[2]

This thomasia grows on flats from near Cranbrook to Israelite Bay in the Avon Wheatbelt, Esperance Plains and Jarrah Forest bioregions of south-western Western Australia.[2][3]

Thomasia dielsii is classified 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 which are potentially at risk.[6]