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FLIP

FLIP: Florida Invasive Plants

Casuarina glauca

Common Name(s): Gray sheoak, suckering Australian-pine, beefwood, Brazilian oak

Origin

Australia

Ecological Impact

Suckers aggressively from widely spreading roots, especially when pruned, creating “local jungles” of dense branches, excluding other vegetation. Displacing and extremely destructive to native plant communities, tending to completely take over areas it invades. documented as invading scrub, coastal strands, maritime hammocks, coastal berms, beach dunes, shell mounds, pine rocklands, and ruderal communities. 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

Evergreen tree that grows up to 70 feet, with a dense, pyramidal shape. Bark is gray-brown, finely fissured, scaly. Branchlets pine-needle-like, green, occasionally waxy, jointed, thin (< 1mm wide), 20-26 cm (8-10 in) long, minutely ridged, glabrous. Leaves reduced to tiny scales, in whorls of 10-17 at joints of branchlets. Flowers unisexual (dioecious), inconspicuous, female in small axillary clusters, male in small terminal spikes; female plants rare in Florida. Fruit a tiny, 1-seeded, winged nutlet (samara), formed in woody cone-like clusters (fruiting heads), these brown, to 1.8 cm (⅔ in) long and 0.9 cm (⅓ in) wide.

Identification Tips

C. equisetifolia has a single trunk and produces viable seeds that are wind- and bird-dispersed; C. glauca produces suckers at the base of the trunk, rarely sets seed in Florida, and has a weeping growth habit.

History

Introduced to Florida in the late 1800s to be used for hardwood and forage, but found to be unsuitable for either purpose. Planted widely in southern Florida as windbreaks, roadside trees, and hedges.

Range

Central and South Florida. Most common in coastal counties as far west as Franklin County in the Panhandle, Dixie on the west coast, and Volusia on the east coast south to Monroe, including the Keys, and Miami-Dade, respectively. Has also been reported from natural areas in St. Johns, Lake, Citrus, Pasco, Polk, Osceola, Highlands, and DeSoto counties.

Management Strategies

Do not plant. Remove plant and root system. Herbicide treatment, basal bark: 10%-20% Garlon® 4. Herbicide treatment, cut stump: 50% Garlon® 3A or 10%-20% Garlon® 4. Remove scaly bark if present. Herbicide treatment, frill/girdle (larger trees): 20% Garlon® 4. Addition of 3% Stalker® will increase consistency on older trees.

Photos

Most photos courtesy of the Atlas of Florida Plants; click for additional plant details.

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Florida Invasive Plants