Asia-Tropical
Indo-China: Myanmar; Thailand; Vietnam
Malesia: Indonesia; Malaysia; Philippines
North Indian Ocean: India - Andaman and Nicobar
Australasia
Australia: Australia - New South Wales, - Queensland
Pacific
Northwestern Pacific: Marshall Islands; Micronesia; Northern Mariana Islands; Palau
South-Central Pacific: French Polynesia
Southwestern Pacific: Fiji; Vanuatu
Casuarina equisetifolia is a deciduous tree that occurs in open, coastal habitats including sand beaches, rocky coasts and sand dunes. Trees can grow to over 100 ft. (30.5 m) in height. The reddish-brown to gray bark is brittle and peels. Branchlets resemble pine needles and are very thin, 4-8 in. (10-20 cm) long and gray-green. Male and female flowers are present on the same plant and are inconspicuous. Male flowers occur in terminal spikes, while the female flowers are in small, axillary clusters. Fruit are tiny, winged nutlets that each contain one seed. The fruits are contained in woody, cone-like structures that are 0.75 in. (2 cm) long.
Australian pines were widely planted in Florida to form windbreaks around canals, agricultural fields, roads and houses.
Australian pines were introduced into Mexico before 1852, to the Caribbean at Barbados in 1870, Hawaii before 1895, and was naturalized in the West Indies and Florida by 1920. The rumor that John Ringling (1866-1936) of circus fame introduced the tree to Florida is not possible as stated. The Australian Pines were around some 14 years before he was born and were naturalized in Florida 16 years before he died. That he could have brought the species to Florida is possible though I would not think probable. Perhaps he planted one in Sarasota, his winter home.
As with many problem plants, the US Department of Agriculture had a hand in the tree’s introduction and proliferation. Seeds were readily available from California by 1908 and it was a common shade tree in Palm Beach by 1921 (the tree can grow eight feet a year, eclipsed only by the Moringa which can easily do 10 feet a year.) It can be trained into a hedge but is extremely vulnerable to fire and intolerant of frost. It also makes an excellent bonsai specimen (see photo on bottom.)
By 1940 it was one of the most widely planted trees in Florida, usually for ditch and canal stabilization as well as a wind break. It was the tree of choice to protect causeways to the Space Center, though artistically interrupted by the Melaleuca, also now on the biological hit list. Several memorable freezes since then has reduce that population but they can still be found along the shores of Indian River lagoon with a good stand unbelievably still at Haulover Canal north of the Space Center. Popular as they were, starting in 1952 cities were crafting ordinances against the species. To cities they pose an enormous financial burden, not only ruining water and sewer mains but buckling streets. Worse, they fall over.