An erect to spreading shrub to 2 metres tall.
It is found in dry sclerophyll forests and woodland, often near creeks, on sandy soils over sandstone.
It grows on the coast, tablelands and central western slopes of New South Wales, from Murwillumbah in northern NSW, to the Budawang Range, with most of its occurrence from the Hunter Valley to Batemans Bay.
Branches are four-ridged (square) and slightly aromatic.
Prostanthera have simple, opposite and usually odorous leaves (a typical Lamiaceae feature). In this species, leaves are in opposite pairs (rarely in 3-leaf whorls), egg-shaped to circular, to 65 mm long and to 40 mm wide, on a petiole to 15 mm long, slightly aromatic.
Flowers have a shape described as labiate (applies to all Lamiaceae flowers) with 5 petals varying in their size, fused at their base, produced in leaf axils. One of the identification features for Prostanthera is that the 5 calyx parts (basal whorl of the flower) are fused into 2 lips.
In this species, flowers are arranged in compressed groups / clusters on the ends of branchlets, each flower with bracteoles about 2.5 mm long at the base, but that fall off as the flower develops.
The petals are white to pale mauve and 12 to 15 mm long with petals fused into a tube for part of their length.
Fruits are mericarps (can be called nutlets). Four are produced produced at the base of the calyx.
Not commonly cultivated, and plants may be hard to source, but it is known to be cultivated. It is likely just one of many species that needs more promotion in cultivation.
It prefers a well-drained sandy soil in full-sun to part shade.
Could likely be pruned to a nice shape. Best approach is a light tip prune after flowering.
A Prostanthera in full bloom is a magnificent sight and there are so many colours to choose from for your garden. These plants are found in all states in varied soil conditions and climate and thus while it may be a challenge to grow some species many are easy in a garden situation.
A few basic growing tips are:
• Good drainage is essential. Raised beds ensure this
• Water new plants until established, weekly or as required.
• Do not over water, as this can induce root rot and fungal infestation.
• They prefer moist root runs.
• Plant drooping is an indicator of dryness
There is a tip from the publication:
“Letters to Garden Lovers”, Australian Home Beautiful, April 1938, to regularly and lightly prune branches all through the year rather than give plants a heavy prune once a year. Be careful not to eliminate flower buds, however.
Positioning of prostantheras as border plants or near pathways is recommended as the mint odour is released when brushed against.
Plants may be grown from fresh seed. However, cuttings are frequently and reliably used, usually semi-hard wood or soft tip material, which strike well in spring or autumn.
Prostanthera is a diverse group of about 100 species, endemic to Australia, occurring in all states. There are still many unresolved taxa and species complexes, with new forms regularly being found. Natural hybrids occur between several species and most species appear to be capable of hybridizing when in cultivation. NSW currently has about 52 species, some of which are species-complex and others which are threatened with extinction.
Some 80% of mints contain aromatic oils within their leaves with oil of cineole being a major component. Prostanthera sieberi, P. incisa and P. staurophylla are quite pleasantly overpowering in their exudates when crushed. Oil from the leaves of some species is distilled for use in cosmetics and as soap additives.
Most Prostanthera species will regenerate from seed after fire with some species exhibiting an ability to reshoot from basal areas and stem buds. The exact response for this species is unknown.
Prostanthera – from the Greek prosthike (προσθήκη) which translates to “addendum”, and anthir (ανθήρ) meaning anther – referring to the anthers which have an appendage of tissue.
prunelloides – resembling species of Prunella, another genus of the Lamiaceae, eg: the naturalised weed *Prunella vulgaris. The resemblance is likely in the leaves and/or clustered flower-heads.
This species is not considered to be at risk of extinction in the wild.
NSW Flora Online (PlantNET) – Prostanthera prunelloides profile page http://anpsa.org.au/APOL2007/apr07-1.html
Wikipedia – Prostanthera prunelloides profile page
Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.
Australian Native Plants Society Australia – Prostanthera information page