Casuarina (Casuarina equisetifolia)
Native Range: Southern Asia, Australia and the Pacific Islands.
How it got here:Introduced in the 1950's to reforest the island after a scale insect wiped out the endemic Cedar forest.
How it spreads: The winged seeds are spread by the wind and in water. Trees are also still planted by people.
This tree is locally called by its genus name Casuarina, but is also known as the Australian Whistling Pine for the noise made by the wind passing through its branches. The Casuarina was introduced to Bermuda from Australia in the 1940’s following the decimation of the Bermuda Cedar forest by an introduced scale insect.
The Casuarina grows quickly and achieves substantial heights, even in poor soil and when exposed to salt spray. These characteristics made it an ideal choice to reforest Bermuda after the cedar blight, but also led to its aggressive invasion of Bermuda’s coasts.
These traits also make Casuarinas likely to blow down in hurricanes, which leads to property damage from falling trees, and coastal erosion as plugs of rock and soil are ripped up by the roots of the falling tree.
Casuarina equisetifolia produce both male and female flowers on the same tree (they are monoecious). The male flowers produce large amounts of pollen, which can be a respiratory irritant to people with asthma.
Casuarinas produce cone-like fruit which open to spread wind-borne seeds. The leaves of the Casuarina are small scales on thin ‘needle-like’ branches. Where Casuarinas grow in dense groves, these needles form a thick blanket under the trees, which prevents any other plants from growing there. In this way, Casuarinas have eliminated habitat for a number of native Bermudian plants.
Removal:A fully grown Casuarina can reach 150 ft (46 m) with a wide spreading root system, so removal of large trees requires professional help. Small trees can be cut down to ground level and make excellent firewood. Ideally Casuarinas should be removed at the seedling or sapling stage. Even small seedlings are remarkably difficult to pull by hand, so tools may be needed.
Further Reading: An Illustrated Guide to Bermuda’s Indigenous and Invasive Plants [PDF, 42MB].