Bunya Pine

Araucaria bidwillii will grow to a height of 50 m (160 ft) with a single unbranched trunk up to 1.5 m (4 ft 11 in) diameter, which has dark brown or black flaky bark. The branches are produced in whorls at regular intervals along the trunk, with leaf-bearing branchlets crowded at their ends. The branches are held more or less horizontally – those towards the top of the trunk may be somewhat ascending, those on the lowest section of the trunk may be somewhat drooping. This arrangement gives the tree a very distinctive egg-shaped silhouette. The leaves are small and rigid with a sharp tip which can easily penetrate the skin. They are narrowly triangular, broad at the base and sessile (without a stem). They measure up to 5 cm (2.0 in) long by 1 cm (0.4 in) wide with fine longitudinal venation, glossy green above and paler underneath. The leaf arrangement is both distichous and decussate (referred to as secondarily distichous) – that is, one pair of leaves are produced on the twig opposite each other, and the next pair above is rotated around the twig 90° to them, and so on. The cones are terminal, the male (or pollen) cone is a spike up to 20 cm (7.9 in) long which matures around October to November. The female (or seed) cone is much larger, reaching up to 30 cm (12 in) long and 20 cm (7.9 in) wide, which is roughly equivalent to a rugby ball. …

At the start of British occupation, A. bidwillii was abundant in southern Queensland, occurring in large groves or sprinkled regularly as an emergent species throughout other forest types on the upper Stanley and Brisbane Rivers, Sunshine Coast hinterland (especially the Blackall Range and Maleny), and also towards and on the Bunya Mountains. Two more natural, but very small and very isolated, populations of the species occur approximately 1,500 km (930 mi) to the north, in the wet tropics region of northeastern Queensland – one close to Cannabullen Falls on the Atherton Tableland, and the other in the Mount Lewis National Park. Today, the southeast Queensland populations exist as very small groves or single trees in its former range, except on and near the Bunya Mountains, where it is still fairly prolific, while the populations in north Queensland remain stable. The limited distribution of A. bidwillii in Australia is in part due to poor seed dispersal, and also the drying out of the Australian continent over the millennia, leading to a reduction of areas with suitable climatic zones for rainforest.

A variety of birds and animals, including sulphur-crested cockatoos (Cacatua galerita), short-eared possums (Trichosurus caninus), fawn-footed melomys (Melomys cervinipes), and wallabies are known to eat the seeds. The cockatoos are also a dispersal agent as they will carry seeds to a distant perch to eat, but may drop them on the way. The suggestion that extinct large animals (initially dinosaurs and later the Australian megafauna) may have been dispersers for the bunya is reasonable, given the size of the seeds and their energy content, but difficult to confirm given the incompleteness of the fossil record for coprolites. A. bidwillii has an unusual cryptogeal seed germination in which the seeds develop to form an underground tuber from which the aerial shoot later emerges. The actual emergence of the seed is then known to occur over several years presumably as a strategy to allow the seedlings to emerge under optimum climatic conditions or, it has been suggested, to avoid fire. This erratic germination has been one of the main problems in silviculture of the species. A problem in small forestry plantations of the bunya pine in Southeast Queensland is the introduction of red deer (Cervus elaphus). Unlike possums and rodents, the deer eat bunya cones while still intact, preventing their dispersal.

Bunya nuts are slow to germinate. A set of 12 seeds sown in Melbourne took an average of about six months to germinate (with the first germinating in three months) and only developed roots after one year. The first leaves form a rosette and are dark brown. The leaves only turn green once the first stem branch occurs. Unlike the mature leaves, the young leaves are relatively soft. As the leaves age they become very hard and sharp. Cuttings can be successful, though they must be taken from erect growing shoots, as cuttings from side shoots will not grow upright. In the highly variable Australian climate, the varied timing of emergence of the seedlings maximises the possibility of at least successful replacement of the parent tree. A test of germination was carried out by Smith starting in 1999. Seeds were extracted from two mature cones collected from the same tree, a cultivated specimen at Petrie, just north of Brisbane (originally the homestead of Thomas Petrie, the son of the first European to report the species). One hundred apparently full seeds were selected and planted into 30 cm by 12 cm plastic tubes commercially filled with sterile potting mix in early February 1999. These were then placed in a shaded area and watered weekly. Four tubes were lost due to being knocked over. Of a total of 100 seeds placed, 87 germinated. …

The genus name Araucaria is taken from the Spanish word Araucanía, the name of the area in Chile where the first species of this genus originated, and/or Araucanos, the Spanish word for the original inhabitants of the area. Hooker coined the species epithet in honour of Bidwill, for his efforts in collecting specimens and bringing them to him.