Tree of the Month – July 2020

Our feature tree this month is the group of trees which often come under the common name of Sheoak, and which includes quite a number of species grouped in two genera, Casuarina and Allocasuarina. Where previously Sheoaks were mostly all described as Casuarina, these were separated into separate genera in around 1980.

Allocasuarina includes around 60 species, all of which are endemic to Australia, while the closely-related Casuarina genus includes about 17 species, which are distributed across Australia, the Indian subcontinent, south-east Asia, islands of the western Pacific, and eastern Africa.

While quite a few different species of Allocasuarina and Casuarina have been used as bonsai, three species of particular interest to VNBC members are Allocasuarina littoralis, or Black Sheoak, Allocasuarina torulosa, or Rose Sheoak, and Casuarina cunninghamiana, or River Sheoak.

Black Sheoak occurs as a medium-sized tree along the eastern coastal areas of Queensland, NSW, ACT, Victoria, and Tasmania, usually growing in woodland and sometimes in tall heath, and often growing in sandy and other poor soils. Rose Sheoak is a medium-sized tree, native to the surrounds of rainforest areas in eastern and coastal Queensland and NSW. River Sheoak naturally occurs as a tallish tree in sunny stream banks and swampy areas from Northern Territory through to Queensland and southern New South Wales.

Casuarina cunninghamiana, River Sheoak

The characteristic fine needle-like foliage and the rough, ridged bark of sheoaks makes them an interesting subject for training as bonsai in a variety of styles.

These trees featured below are just a small selection of VNBC members’ trees displayed in recent exhibitions by the club.