Origin
Australia, South Pacific Islands, Southeast Asia.
Ecological Impact
Introduced to Florida in the late 1800s. Naturalized since the early 1900s along coastal dunes. Planted extensively in the southern half of the state as windbreaks and shade trees. Seeds freely throughout the area and has spread rapidly. Salt tolerant, growing even in front-line dunes. With rapid growth, dense shade, dense litter accumulation, and other competitive advantages, displacing and extremely destructive to native vegetation. Competition is also inhibited by allelopathy. Can encourage beach erosion by displacing deep-rooted native vegetation. Interferes with nesting of endangered sea turtles and the American crocodile. Listed as a Category I invasive species by the Florida Exotic Pest Plant Council and listed as a prohibited aquatic plant and noxious weed by the Florida Department of Agriculture and Consumer Services.
Description
Can grow up to 150 ft, with open crown. Branchlets are thin and grayish green. Leaves are tiny, scalelike, in whorls of 6-8, and very dark green. Flowers are tiny, unisexual, on same tree. Fruits occur in woody, conelike clusters.
Identification Tips
Although it has needle-like leaves and conelike fruits, this tree is not a member of the Pine family, Pinaceae. There are three species of Casuarina in Florida: C. equisetifolia, C. glauca, and C. cunninghamiana. All are similar, differing only slightly in the size of leaflets and fruits. All are listed as invasive by the Florida Exotic Pest Plant Council. For help in distinguishing between the three species, refer to “Field Guide to Identify the Common Casuarina (Australian Pine) Species in Florida”, by William S. Castle.
History
Though it is now recognized to be shallow-rooted and ill-suited to the purpose, Australian pine was widely planted along canals and ditches and along coastal and inland shorelines to stabilize soil and reduce erosion. It was also planted for shade and for lumber. Because it has become so ubiquitous in Florida, some people downplay its detrimental effect on the environment and champion this tree, resisting efforts to replace it with native trees and citing its value as a source of shade and, more dubiously, wildlife habitat.
Range
Southern half of peninsular Florida; more common in coastal areas.
Management Strategies
Raking and removal of leaf litter, cones, and seeds should be done whenever possible, to reduce reseeding and allelopathic effects on surrounding native vegetation.