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An erect or spreading shrub growing to a height and spread to 1.5 metres.
It is found naturally in dry sclerophyll woodland and shrubland, often in gravelly or sandy soil, in the eastern half of New South Wales from the central and northern coastal subdivisions through to the tablelands, slopes and the western plains, and into Queensland and Victoria.
The whole plant is aromatic and stems are somewhat square. Branches are densely covered with short hairs.
Prostanthera have simple, opposite and usually odorous leaves. In this species, leaves are mostly linear-elliptic to 1 cm long and to 0.2 cm wide, mid-green coloured, often with a maroon tinge, margins are entire and curved down with the tips blunt.
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, the flowers are pink to purple-mauve, with petals forming a bell-shaped tube, with dark red, maroon or purple dots in the throat, to 10 mm long. Flowers are arranged singularly at the base of paired leaves, forming leafy clusters and occur in spring.
Fruits – 4 tiny nutlets (mericarps) produced at the base of the calyx.
This species is available from some online nurseries and would be a nice addition to any garden. Grow in a sunny to partially shaded position and provide good soil drainage; sandy soil is likely the most optimal. Tip prune after flowering to promote density and flowering the next season.
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.
Plants may be grown from fresh seed. However, cuttings are frequently and reliably used, usually semi-hardwood 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 cineol being a major component. Prostanthera sieberi, P. incisa and P. staurophylla are quite pleasantly overpowering due to their exudates when crushed.
Oil from the leaves of some species is distilled for use in cosmetics and as soap additives.
Most Prostanthera 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.
howelliae – honours Mrs T.J. Howell, after whom botanist William Blakely (1875 – 1941) named the species, stating that Mrs Howell had ‘for a number of years… taken a keen interest in the native flora’.
This species is not considered to be at risk of extinction in the wild.
NSW Flora Online (PlantNET) – Prostanthera howelliae profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Prostanthera~howelliae
Wikipedia – Prostanthera howelliae profile page https://resources.austplants.com.au/wp-admin/post.php?post=8191&action=edit