Most of the continent of Australia is subtropical, with the Tropic of Cancer passing just through the northern part of the continent. Subtropical climates are generally warm with wet summers and drier winters. Winter temperatures rarely dip below freezing and frost hardly ever occurs, similar to the climate of central and northern Florida. The eastern part of Australia along the coast is subtropical rain forest, moving to drier areas inland and desert to the west. This warm, wet climate along the coast and the Great Dividing Range mountains support a diverse, rich selection of flora found nowhere else in the world.
The floral emblem of the Australian subtropical state of New South Wales is the waratah plant (scientific name Telopea speciosissima). Waratah is an evergreen shrub that reaches 10 to 15 feet tall. It has 5 to 10 inch long thick green leaves that are heavily toothed. The most spectacular part of this plant is its flowers. They are spherical surrounded by numerous colored bracts. The flowers are typically bright red but white varieties have been created as well. The stem has a lumpy ball at the base called a lignotuber which may be half buried or entirely underground. This stores nutrients so the plant can re-sprout after a brush fire which occurs often in its natural range.
Waratahs like full morning sun with afternoon shade and tolerate poor soils as long as it drains well. They need to remain moist, but do not respond well to wet or soggy soil.
The cabbage palm (scientific name Livistona australis) is native to the wet subtropical and tropical areas throughout the eastern coast of Australia. It grows to 40 feet tall and may develop a trunk up to 12 inches in diameter. It has large 3 to 5 foot long fan-shaped palm fronds on top of a single smooth gray trunk. They typically are found growing in swampy and low areas right up to the edge of the ocean. They are salt tolerant and wind resistant.
Cabbage palms need regular water and full sun. They are frost-tolerant to 22 degrees which makes them a good choice for USDA hardiness zones 9 and warmer.
The bunya-bunya tree (scientific name Araucaria bidwillii) is a large evergreen conifer tree that is native to the subtropical mountainous rain forests of south east and northern Queensland. It grows up to 150 high with long drooping branches. Older trees produce football sized cones that weigh up to 15 pounds. It has wide thick leaf like needles with pointed ends. Two of its closest relatives are the monkey puzzle tree and the Norfolk Island pine.
Bunya-bunya trees will grow in USDA zones 9 and warmer. It needs full sun and tolerates a wide range of soil types if they drain well. Young plants need to be watered regularly, but mature trees are very drought resistant.