fbpx

Prostanthera cuneata

Alpine Mint Bush

Family: Lamiaceae

An attractive and dense small shrub to 1 metre tall and to 1.5 metres wide.

It grows in NSW as far north as Canberra, and then extends south-west through the Alpine region; growing south-west through Victoria to as far as east of Marysville and Tanjil Bren.

It grows in alpine shrubland and dry sclerophyll forest, often beneath snow gums and sometimes dominating the groundlayer.

Prostanthera have simple, opposite and usually odorous leaves. In this species, the strongly aromatic leaves are roughly oval in shape and taper to the base, to 5 mm long and 3.5 mm wide; dark green above and paler beneath.

Flowers have a shape described as labiate (applied to all Lamiaceae flowers) with petals varying in their size, purple to lilac, produced in leaf axils. One of the identification features for Prostanthera is that the 5 calyx parts (sepals; basal whorl of the flower) are fused into 2 lips. In this species, flowers are to 2 cm long, white with purple to red-coloured blotches in the throat, produced solitarily in leaf axils but crowded in leafy clusters. They are said to be sweetly fragrant; occurring between November and April.

Fruits are mericarps (can be called nutlets). Four are produced produced at the base of the calyx.

In the garden

A very attractive and useful shrub to grow. It is commonly cultivated and is recommended for cooler areas. Will likely not thrive in humid and tropical areas. It is commonly grown on the west coast of England.

Growth habit, foliage and flowers are attractive features. Tip pruning will create a denser plant at close to ground level.

‘Alpine Gold’ is a cultivar with green and gold variegated foliage.

Best grown on a free draining soil with some enrichment. Keep water up to it in dry times. Plant in large groups for a nice effect – especially on a slope.

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

Positioning of prostantheras as border plants or near pathways is recommended as the mint odour is released when brushed against.

Propagation

Propagate from cuttings.

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.

Other information

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.

Likely regenerates from seed after fire, possibly after 12 months.

Prostanthera – from the Greek prosthike (προσθήκη) which translates to “addendum” (root of prosthetic), and anthir (ανθήρ) meaning anther – referring to the anthers which have an appendage of tissue.

cuneata – Latin meaning ‘cuneate’ – which is a wedge-shape, referring to the foliage which are widest at the top.

This species is not considered to be at risk of extinction in the wild.

NSW Flora Online (PlantNET) – Prostanthera cuneata profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Prostanthera~cuneata

Gardening with Angus – Prostanthera cuneata profile page https://www.gardeningwithangus.com.au/prostanthera-cuneata-alpine-mint-bush/\

Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.

By Warren and Gloria Sheather. Editing and additional text by Dan Clarke.