Prostanthera is a genus of about 90 species which occur only in Australia. They are known generally as “mint bushes” because of the aromatic foliage of many species. As a member of the Lamiaceae, Prostanthera is related to a number of culinary herbs such as mint, thyme, oregano and sage.
Prostanthera calycina is a spreading shrub to about 50 cm in height. The leaves are oval to oblong, about 10 mm in diameter and covered in microscopic hairs and highly aromatic. The tubular flowers occur in spring and early summer and are usually dull red in colour subtended by a large green or maroon calyx.
P.calycina is best suited to dry climates and can be short lived in areas with humid summers. It prefers a well drained position and will tolerate full sun as well as partial shade. Prostantheras respond to well to annual fertilising after flowering and are not as sensitive as some other Australian plants to phosphorus.
Propagation is easy from cuttings but seed can be slow to germinate. It can also be grafted using one of hardier mint bushes such as P.nivea as rootstock. Unlike most other prostantheras which can be grafted onto the related (and extremely hardy) Westringia fruticosa, P.calycina is not compatible with that species.
* EPBC Act = Environment Protection and Biodiversity Conservation Act 1999;
ROTAP = Rare or Threatened Australian Plants (Briggs and Leigh, 1988)
For further information refer the Australian Plants at Risk page
Photo: Brian Walters