The weeping peppermint (Agonis flexuosa) is a species of tree that grows in the south-west of Western Australia. It is easily the most common of the Agonis species. and is one of the most recognisable trees of Western Australia, being commonly grown in parks and on road verges in Perth.
It is commonly known as Western Australian peppermint, Swan River peppermint or just peppermint, and willow myrtle for its weeping habit.
The weeping peppermint occurs mainly as a small and robust tree, usually less than 10 metres tall although it has been known to grow to 15 metres. It has a fibrous, brown bark, and long narrow, dull green leaves, with tightly clustered inflorescences of small white flowers in the axes. It has a weeping habit, and look remarkably like the weeping willow from a distance. Leaves are narrow and reach a length of 150mm. It is readily identified by the powerful odour of peppermint emitted when the leaves are crushed or torn. It flowers between August and December. The fruit is a hard capsule, 3-4mm across, with three valves containing many very small seeds.
The genus name Agonis comes from the Greek agon, "a cluster" referring to the arrangement of the fruits. The species name flexuosa is Latin for "full of bends". referring to the zig-zag course of the stem, which changes direction at each leaf node. It was originally placed in the Leptospermum genus by Spangel in 1819, but Schauer placed it in Agonis in 1844.
This tree occurs in a subcoastal strip from just north of Perth, southward through the Swan Coastal Plain, then along the coast to outlying records east of Bremer Bay (34º23'S. The habitat includes limestone heath, stable dunes and sandy soils, usually inland from the coast and it also grows as an understory plant in the tuart forest.
In cultivation it is used in mass plantings, such as street trees, and has been introduced to Rottnest and Garden Islands near its native region. Agonis flexuosa is an attractive garden or specimen tree in temperate climates. *However, care must be exercised in selecting it for small areas, as in a yard setting. Quick growing, the tree produces a large amount of detritus and its trunk sometimes becomes large and disproportionate to the rest of the tree. Here weeping peppermints grow on foreshore parkland on the Swan River at Keanes Point, Peppermint Grove.
*NOTE: We have three of these trees in our garden (two were self-sown). Two of them have single trunks but the third and latest tree is multi-trunked. They grow rather tall and they have not proven too large for either our front or back garden. They do drop small leaves but we've never noticed them to be very 'messy' trees that necessitate cleaning up under them.
I understand that some people can be very allergic to these trees when they are in flower. A friend of my daughter's who nursed at Busselton hospital (it is near there where the tuart trees grow and there are weeping peppermints scattered throughout the region) said they would quite often have patients come to the hospital whose asthma was made worse because of these trees. Neither Phil nor I have noticed they cause us too many problems in that regard. We tend to find the wattles give us hay fever.