Casuarina equisetifolia, locally known as Filao is a member of the Casurainaceae family. This evergreen tree is distinguished by its pine-needle-like leaves and irregular crown, bearing some resemblance to coniferous plants. Although it can reach a maximum of 50 meters, the tree generally does not reach beyond 15 to 25 meters in height. Its bark is reddish brown to grey, rough, brittle and peeling. Branchlets are greyish or green, thin and jointed and measure between 10 to 20 centimeters. The branchlets hold the leaves which occur in tiny scales, arranged in 6 to 8 whorls which encircle the joints of branchlets. A monoecious tree, female flowers occur in small axillary clusters while male flowers occur in terminal spikes. The tree bears a tiny, one-seeded, winged nutlet, formed in woody clusters resembling cones.
 Global Invasive Species Database. 2018. Species profile: Casuarina equisetifolia. Downloaded from http://www.iucngisd.org/gisd/species.php?sc=365 on 19-08-2018.
These Casuarina species can be found in open coastal strands such as sandy beaches and dunes, rocky shores, sandbars and around estuarine and mangrove habitats. They are found throughout tropical and subtropical climates. Its native habitat is considered to be coastal herbaceous swamps and broad-leaved hammock communities. Although not a legume, the species is able to fix atmospheric nitrogen through microbial associations in its root nodules. It is salt tolerant, wind resistant and adaptable to moderately poor soils. The first seedlings of the species were brought to Mauritius in 1778. Casuarina has been widely planted along the coastlines of Mauritius as part of a tree and water conservation programme which started in the late nineteenth century and continued up until the mid1970s. This programme aimed to protect the coast against beach erosion and sea gusts. Although it has been considered to have naturalized, the use of casuarina threatens the survival of native plants and animals on coastal strands. Fast growing and producing shade and a thick blanket of leaves and seeds, the species alters light, temperature, soil chemistry and the hydrology of the site in which it is planted. It forms dense monoculture thickets, displacing native dune and beach plant species.
up to now, there are no wide scale measures to control casuarinas. On some pilot sites, these filaos have been removed to be replaced with native coastal species.
 Potgieter, Luke , David Mark Richardson, and John R Wilson. 2014. "Casuarina: Biogeography and ecology of an important tree genus in a changing world." Biological Invasions 16 (3): 609–633.
In Mauritius and other parts of the world, the wood has traditionally been used for beams, boat building, electric poles, fences, furniture, paving materials, pilings, roofing shingles, tool handles, and even wagon wheels.