Araucaria bidwillii, commonly known as the bunya pine (/ˈbʌnjə/), banya or bunya-bunya, is a large evergreen coniferous tree in the family Araucariaceae which is endemic to Australia. Its natural range is southeast Queensland with two very small, disjunct populations in northeast Queensland's World Heritage listed Wet Tropics. There are many planted specimens on the Atherton Tableland, in New South Wales, and around the Perth metropolitan area, and it has also been widely planted in other parts of the world. They are very tall trees – the tallest living individual is in Bunya Mountains National Park and was reported by Robert Van Pelt in January 2003 to be 51.5 m (169 ft) in height.

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 maturity, which occurs from December through to March, female cones are green with 50–100 pointed segments, each of which encloses a seed, and they can weigh up to 10 kg. Both seed and pollen cones are some of the largest of all conifer species.

The edible seeds, known as bunya nuts, measure between 2.5 cm (1.0 in) and 5 cm (2.0 in) long and are ovoid to long-elliptic.

In the 1970s, botanists Hallé, Oldeman and Tomlinson studied the growth patterns of tropical trees and described a set of 23 "architectural models", named after various botanists, which can be seen as different growth strategy to occupy space. Araucaria bidwillii, like many species from the Araucariaceae family and the fir genus, changes its structural model over time. Initially its follows Massart's model (a single, upright trunk that grows steadily and produces neat, horizontal layers of branches at regular intervals) and gradually changes to Rauh's model (like Massart's, but here each branch grows structurally similar to the trunk, with smaller branches branching off of it.)

The trees' pollen cones appear in April and mature in September or October. The cones require fifteen months to mature, and the cones fall 17 to 18 months after pollination in late January to early March from the coast to the current Bunya Mountains. When there is heavy rainfall or drought, pollination may vary.

The species was described by the English botanist William Jackson Hooker in 1843, based on material collected in the "Mount Brisbane range of hills, 70 miles N.W. of Moreton Bay" by John Carne Bidwill in 1842. Hooker states in his paper that Bidwill took "not only branches and cones and male flowers, but also a healthy young living plant" to England where Hooker set about describing the new species, and his paper (titled "Figure and description of a new species of Araucaria from Moreton Bay, New Holland") was published in his own journal London Journal of Botany.