Prostanthera incisa, or cut-leaf mintbush, is a shrubby plant native to rocky mountain tops of Eastern Australia. It has an attractive purple flower. The leaves are highly aromatic, ovate-lanceolate, 1–3 cm long, and teethed.
Robert Brown described the species in his 1810 work Prodromus Florae Novae Hollandiae et Insulae Van Diemen, and it still bears its original name.
There are two recognized varieties:
- P. incisa var. incisa
- P. incisa var. pubescens
Distribution and habitat
Prostanthera incisa is found along the New South Wales coastline from Mount Warning near the Queensland border all the way to Victoria, as well as the Central Tablelands. It is found in sheltered sites in rainforest margins or sclerophyll forest under such trees as Sydney blue gum (Eucalyptus saligna), cabbage gum (E. amplifolia), Sydney peppermint (E. piperita), red bloodwood (Corymbia gummifera) or turpentine (Syncarpia glomulifera). It can also occur in scrub along watercourses in association with river she-oak (Casuarina cunninghamiana).
The leaves and green twigs are distilled for their essential oils. The dried leaf of a specific flavouring chemotype of P. incisa var. incisa is also sold under the trade name of native mint. However, this can be confusing because Australia also has true native Mentha species.
First grown in England in 1824, P. incisa var. incisa is cultivated on a small-scale commercial basis for essential oil production and for bushfood spice. P. incisa prefers sheltered sites in well-drained acidic soils, and in poorly drained soils it can be susceptible to root-rot. It has reasonable frost tolerance down to −5 °. It is a fast-growing shrub, and consequently can be harvested within the first year. When pruned back to a height of 50 cm it reshoots readily.
Propagation is by seed or cutting material of firm young growth.
Occasionally this species is confused with the related Prostanthera ovalifolia.
- "Prostanthera incisa R.Br.". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government.
- B.J.Conn. "New South Wales Flora Online: Prostanthera incisa". Royal Botanic Gardens & Domain Trust, Sydney, Australia. Retrieved 10 April 2014.
- Benson, Doug; McDougall, Lyn (1997). "Ecology of Sydney Plant Species Part 5 Dicotyledon families Flacourtiaceae to Myrsinaceae" (PDF). Cunninghamia. 5 (2): 330–544.
- Zhao, J., Agboola, S., Functional Properties of Australian Bushfoods - A Report for the Rural Industries Research and Development Corporation, 2007, RIRDC Publication No 07/030 
- Elliot, Rodger W.; Jones, David L.; Blake, Trevor (1997). Encyclopaedia of Australian Plants Suitable for Cultivation: Volume 7 – N-Po. Port Melbourne: Lothian Press. p. 26; 221. ISBN 0-85091-634-8.