Last time we discussed and described the westringias, members of the Lamiaceae plant family. This time it is the turn of another group of Australian plants from the same family.
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The prostantheras or mint bushes are unique Australian plants that occur naturally nowhere else in the world. They are similar in many ways to their cousins the westringias but differ in having strongly aromatic foliage.
Most mint bushes grow into small to medium shrubs with a few groundcovers and tall shrubs in the group.
Their flowers are irregular in shape with two distinctive lips. Flowers come in a range of colours.
Prostantheras have two flowing periods. Most put on their blooming display in spring while others wait until midsummer to flower.
They respond to light pruning and do best in full sun to medium shade. In company with the westringias, they propagate readily from cuttings.
Prostantheras are double-barrelled plants. Not only do they reward the gardener with abundant flowers, but their aromatic foliage is a bonus. Mint bushes are often grown beside paths so that the foliage aroma is released as you brush past.
The round-leaved mint bush would be at home as a foreground specimen in native shrubberies.
Prostanthera ovalifolia, oval-leaved mint bush, is probably the most widely grown species. This medium shrub, as the name implies, has oval-shaped leaves. Spring flowers are usually mauve, purple or bluish-purple.
A white-flowered form is sometimes available as one with variegated foliage. Blooms are both profuse and conspicious.
Once flowers fade, cut off each stem behind the spent flowers. Without pruning, plants may become a trifle straggly.
This hardy and free-flowering species will develop into a colourful screening plant.
Prostanthera rotundifolia, round-leaved mint bush, is a medium, rounded shrub with round, aromatic leaves. In spring, plants produce large numbers of blue flowers. There is also a white-flowered form.
The round-leaved mint bush would be at home as a foreground specimen in native shrubberies. The species could also be planted under eucalypts to create a woodland effect. This mint bush is widely distributed and is found in NSW, Victoria and Tasmania.
Prostanthera cuneata, the alpine mint bush, is found in the high altitude areas of NSW, Victoria and Tasmania. This delightful, dwarf to medium-spreading shrub has small, strongly aromatic leaves.
Flowers are 1.5cm long and white with coloured blotches in the throat. The long flowering period extends from November to April. Growth habit, foliage and flowers are attractive features.
There is a cultivar known as “Alpine Gold” that has green and gold variegated foliage. This mint bush would be and attractive border plant in native gardens.
Prostanthera cuneata is often the dominant understorey plant in alpine areas.
Prostanthera lasianthos is known as the Victorian Christmas bush and will develop into a tall shrub. The glossy leaves are lance-like in shape. Flowers are carried in sprays and are usually white.
There is also a pink flowering form that grows at Apsley Falls. Both forms bloom in mid summer. This aromatic and decorative shrub has proved to be hardy and free-flowering.
Try a few mint bushes in the garden for colour and perfume.
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