Prostanthera calycina

Prostanthera calycina is a more or less prostrate shrub that typically grows to a height of about 0.5 m (1 ft 8 in) and has more or less cylindrical, hairy branches. The leaves are well-spaced along the branchlets, elliptic to oblong, 4–14 mm (0.16–0.55 in) long and 3–5 mm (0.12–0.20 in) wide on a densely hairy petiole 0.8–1.4 mm (0.031–0.055 in) long. The leaves are strongly aromatic when crushed. The flowers are arranged singly in leaf axils on a hairy pedicel 2.5–4.5 mm (0.098–0.177 in) long. The sepals are 8–14 mm (0.31–0.55 in) long forming a tube 6–8 mm (0.24–0.31 in) long with two lobes 4–6 mm (0.16–0.24 in) long and 5–7 mm (0.20–0.28 in) wide. The petals are 17.5–22 mm (0.69–0.87 in) long forming a tube 13–15 mm (0.51–0.59 in) long with two lips. The middle lobe on the lower lip is about 4 mm (0.16 in) long and 3 mm (0.12 in) wide, the side lobes about 3 mm (0.12 in) long. The upper lip has two lobes about 5 mm (0.20 in) long and joined but with a small notch between them. Flowering occurs between September and December.[3][4][5]

Prostanthera calycina was first formally described in 1870 by George Bentham from an unpublished description by Ferdinand von Mueller and the description was published in Flora Australiensis.[6][7]

West coast mintbush is only known from the Eyre Peninsula in South Australia where it usually grows on limestone outcrops in mallee vegetation.[5]

West coast mintbush is classified as "vulnerable" under the Australian Government Environment Protection and Biodiversity Conservation Act 1999 and the South Australian Government National Parks and Wildlife Act 1972. The main threats to the species include grazing, habitat fragmentation and road maintenance.[5]

This mintbush is easily propagated from cuttings or by grafting onto Prostanthera nivea and grows best in dry climates in well drained soil.[5][8]