How2Day: Australian Tropical Trees

Queensland, Australia lies in the tropics to subtropics and has trees that are very different from anywhere else in the world. Plant species here have been isolated from other habitats and evolved independently. This has allowed many species, such as the southern hemisphere conifers, to survive the ages intact. They are living examples of prehistoric evolutionary steps that died off in the rest of the world.

Bunya bunya pines (Araucaria bidwillii) are evergreen conifers native to subtropical southern Queensland, Australia, with a few populations extending into the tropical north. The bunya bunya pine is most closely related to Norfolk Island pines and monkey puzzle trees. It has an upright, single trunk and can grow to 150 feet tall, with a very distinct rounded crown. The branches radiate from the trunk in whorls of five and are bare except for the foliage at the tips. The leaves are pointed ovals that get 2 inches long. They are an evolutionary step between leaves and needles. The cones are very large and can weigh up to 15 pounds. Although bunya bunya pines are native to the tropics, they can withstand cooler climates outside their native range. They are often planted in New South Wales and in Southern California. They tolerate most soil types as long as they drain well.

Macadamia nut trees (Macadamia integrifolia) are native to the rain forests of southeastern Queensland and are the only food crop produced on a large scale that is native to Australia. Although they are rare in their native habitat, cultivated trees are widely grown in Australia and in other tropical and subtropical climates around the world. Macadamia trees grow to 45 feet tall and have dark-green, glossy leaves with wavy edges, 8 inches long and half as wide. They produce up to 12-inch-long hanging bunches of small, white flowers that develop into the edible nuts. Macadamia trees grow best when year round temperatures are above 60 degrees Fahrenheit. They like slightly acidic well drained soil with enough organic matter.

Australian fan palms (Licuala ramsayi) are native to the very wet tropical coast of northeastern Queensland. They are most often found as understory trees, in the dense rain forests at low elevations. The Australian fan palm grows has a single, slender trunk and grows to a height of 45 to 60 feet. It usually has 9 to 12 fronds that are fan-shaped and radiate from the crown of the tree making it look like a tall umbrella. The Australian fan palm is a true tropical and does not tolerate frost. It is tolerant of many soil types and is most often found in very wet areas, often in swamps.

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