Family: Asphodelaceae
Species.: Xanthorrhoea johnsonii A.T.Lee
Common name: Grass Tree - English: Johnson's Grass Tree
Etymology
The species name honours the Australian botanist LAS Johnson.
Description
Xanthorrhoea johnsonii is a spectacular, slow-growing grass with an underground trunk. What is visible above ground are the remnants of the leaf bases, which, once exhausted, form a thick, blackened trunk reminiscent of that of a cycad. Columnar in shape, the plant can grow up to 5 metres tall and may branch if the growing point is damaged.
From the top of the trunk emerges a mass of bright green, long, thin, yet firm, grass-like leaves that extend for about 1 metre and arch gracefully over the trunk. The needle-like foliage reduces moisture loss during hot periods, making the plant drought-resistant.
The root system is shallow and primarily functions for anchorage. The active roots are black and fleshy and can be easily damaged. Mycorrhizal fungi colonise the roots, playing a crucial role in nutrient uptake in poor soils and protecting the roots from certain pathogenic fungi.
The flowers develop on a long spike above a bare section known as a scape, which can grow 2–3 cm per day and reach a total length of up to four metres in some instances. The honey-scented flowers, usually appearing in spring, are creamy white and arranged along these long spikes. They are very attractive to birds, bees, and butterflies, and forest fires can stimulate flowering.
These plants are evergreen shrubs; the thin, firm, light green, grass-like leaves emerge from the top of the trunk and spread to about 90 cm, arching elegantly. During winter, the crown turns yellow-green.
Habitat
Native to Eastern Australia.
Properties and Uses
The older foliage is robust—hence one of its common names, “steel grass”—and is widely used in floral design, as it can be bent and rolled without breaking.
Notes and Trivia
Known for their long, grass-like leaves and spectacular spear-shaped flower spikes that can reach several metres in height, these plants exhibit extraordinary resilience. They thrive in poor soil and recover quickly from bushfires, which encourage flowering. They take decades to fully mature and can live up to 600 years.
With graceful, dense foliage that sways in the wind, Xanthorrhoea johnsonii thrives in sunny, well-drained locations in the Heller Garden. Its robust profile is iconic, and spectacular specimens can be observed along the park's paths. The tall, woody flower spikes—reminiscent of a beautiful bottlebrush of tiny flowers—are this species' unique and striking feature.