The Agonis genus is only found in south-west Western Australia. It is a small genus of some 12 species. The genus is part of the myrtle family (Myrtaceae) and consists of evergreen shrubs and trees. The bark of these plants is fibrous.
Probably the best known and certainly the most widely grown is Agonis flexuosa (WA peppermint) which matures as a medium-sized tree. The leaves are linear and often quite small. The common name for the Agonis is ‘peppermint’ because of the aromatic oil which the leaves contain and which is released when the leaves are crushed. The flowers are similar to those of the leptospermum (tea-tree) but are clustered tightly in globular heads. They are small and white (very occasionally pink) and are followed by small, woody capsules of 3 compartments. It is an attractive weeping specimen suited as a windbreak or shade tree.
The variety A.f.nana grows to 1.5 metres and is a very hardy medium shrub. It makes a useful specimen or rockery plant and can also be used as a windbreak. It produces small white flowers in summer. New growth in the spring is an attractive red colour. It is drought and frost tolerant and is attractive to insects, which in turn attract birds.
Agonis linearifolia (swamp peppermint) is found in its wild state along the boggy edges of streams and swamps. It is an adaptable shrubby species with an upright habit. The leaves are narrow with soft pointed tips. Its extended flowering season of small white blooms means it is popular as a cut flower. It is also a good choice for a windbreak or as a screening plant. It grows to a height of 5 metres with a spread of about 3 metres. This plant is an attraction to nectar feeding birds. It also attracts insects which then attract birds.
Agonis parviceps is also known as the fine ti-tree. It grows to 2 metres and has small white flowers in spring. It will tolerate some wetness.
Agonis juniperina is also known as the Juniper Myrtle. It grows to 10 metres with a 5 metre spread. It is an upright species with fibrous bark and often pendulous branches. The leaves are small and dense along the branches. Clusters of small, white flowers are produced in February and March and again in August and November. It is suited to coastal conditions if afforded some protection and will tolerate light frosts.
This adaptable genus is almost pest-free. It is suited to full sun and will grow in a wide variety of soil types providing drainage is good. The plants can be tip pruned at any time or pruned more heavily immediately after flowering. This will promote bushier growth.