Allocasuarina littoralis

black she-oak


Allocasuarina littoralis

(Salisb.) L.A.S.Johnson 1982

pronounced: al-low-kaz-yoo-ar-EE-nuh lit-tor-AH-liss

(Casuariaceae — the she-oak family)


common names: black she-oak

native 4Allocasuarina is from the Greek αλλως (allos), otherwise, like, and the Malay word kasuäri, the Cassowary – like Casuarina. This genus was separated out from the Casuarinas in the mid 1980s. Littoralis is a misspelling of the Latin litoralis, of/guarding the sea-shore. Despite its name, the Black She-oak will do well in both inland and coastal areas.

The tree pictured is on the nature strip in Barbarra Street, Picnic Bay, at the end of a line of Neem trees, on the northern side of its junction with Granite Street.

The leaves of the trees in this genus and the Casuarinas are much reduced to minute scales (called leaf-teeth) encircling each joint, and the photosynthesizing function is transferred to the stems. The long segmented branchlets function as leaves. Formally termed cladodes, the branchlets somewhat resemble pine needles. Some species are monoecious, and others dioecious. In the former case, the unisexual flowers are segregated in different inflorescences. The flowers are sometimes solitary, in axils. The fruits are non-fleshy and indehiscent.

The Black She-oak is native to all the east coast Australian states and Tasmania. It is a fast-growing tree that at certain times of the year will become a dark colour, hence the name. It grows 4 – 10 m in height, and is usually dioecious. As I have seen plenty of male flowers on this particular tree, but have seen neither female flowers nor fruits, I believe it to be a male tree.

The branchlets are to 20 (rarely 35 cm) long, the articles 4 – 10 mm long, and less than 1 mm in diameter, with 6 – 8 leaf-teeth (rarely 5 or 9) at each joint. The trees only rarely fruit, and the fruits are greater in diameter than in length, on peduncles 4 – 20 mm long, the cone body 10 – 30 (rarely 45) mm long, 8 – 20 mm in diameter.

These trees are very suitable for streetscapes and tighter planting locations such as windbreaks. When planted en masse, they give a solid screen of evergreen foliage, and are good at blocking vision. They are low-maintenance trees, except for the fallen cladodes that may require periodic removal. The small cone-like fruits also present few problems. In a forest situation, the fallen cladodes form a dense, soft mat beneath the trees, preventing the development of undergrowth, and making she-oak woods remarkably quiet.

As with legumes, she-oak roots possess nodules containing symbiotic nitrogen-fixing bacteria. This fact, together with their highly drought-adapted foliage, enables she-oaks to thrive in very poor soil and semi-arid areas. However, she-oaks are much less bushfire-tolerant than eucalypts.
Having a pleasant rounded shape, Allocasuarina littoralis is one of the most attractive of the she-oaks, and in some areas provides food and shelter for Black Cockatoos. It is a food plant for the larvae of the She-Oak Moth, Pernattia pusilla.

The she-oaks all produce timber that can be used for turning and cabinet work. It is dense, and very hard with a beautiful grain. The best timber is at the base of the tree, where brighly coloured wood with a good figure is found. The heartwood is pink to reddish brown, sometimes with darker blackish streaks. The rather well-defined sapwood is a light yellowish brown. Very large medullary rays produce a lace-like pattern on quarter-sawn surfaces. The grain is straight to slightly interlocked, and there is a moderate amount of natural lustre. The wood finishes well, although timber from the denser species can be difficult to work.

Photographs taken 2009, 2012, Picnic Bay
Page last updated 4th October  2018