Fiddlewood (Citharexylum spinosum)

Introduction:

Citharexylum spinosum (fiddlewood) is a tree that is commonly planted for its multi-seasonal aesthetic appeal. After escape, it can cause problems by forming dense thickets that choke out other vegetation. In addition, its roots are very aggressive and cause damage to pipes and underground services. Efforts to monitor this plant are underway in many areas, namely Hawaii, where it has spread to several islands.

Description:

Citharexylum spinosum is an evergreen tree that can be up to 50 feet tall. It has no spines and has smooth, quadrangular twigs. Its leaves are up to 8 inches long, smooth and oval or oblong. The leaves also narrow at the base to a short stem, are coarse-toothed or entire, pointed at the tip, and are opposite or in groups of three. Fragrant, white, tubular five-parted flowers, each about 0.3 inch long, are borne in narrow clusters, which are 4 to 12 inches long, branched below or not. Flowers on C. spinosum are functionally unisexual and the trees are dioecious. The fruits of Citharexylum spinosum are globose, 0.25 in (0.60cm) in diameter, immaturely red or orange and purplish to black when ripe. The leaves turn a browish gold colour between February and May. The bark of C. spinosum is light brown, and becomes fissured as it ages. Fiddlewood forms crowded stands even in undisturbed habitats.

Occurs in:

Agricultural areas, coastland, ruderal/disturbed, urban areas.

Habitat description:

Citharexylum spinosum generally grows in wet habitats below 500 metres. It has been found in dry habitats at different elevations, where it

adapts by dropping its leaves during the dry season.

General impacts:

Citharexylum spinosum is able to form a dense canopy, choking out other vegetation. Because of its aggressive roots, which can damage pipes and other underground services, C. spinosum is no longer desirable in Australia and other parts of the world. C. spinosum is able to form a dense canopy, choking out other vegetation. Because of its aggressive roots, which can damage pipes and other underground services, C. spinosum is no longer desirable in Australia and other parts of the world.

Uses:

Citharexylum spinosum is cultivated as a street tree and is a popular ornamental in many tropical and subtropical regions. The leaves of C. spinosum turn orange prior to dropping, which is part of the reason for its appeal. The tree is also attractive because of its fragrant white flowers. People in the Carribean use the wood of C. spinosum to make stringed instruments and cabinets.

Notes:

During the dry season, Citharexylum spinosum is deciduous.

Geographical range:

Native range: United States (Florida), West Indes, South America.

Known introduced range:United States (Hawaii), French Polynesia, Australia, Fiji, New Caledonia.

Local dispersal methods:

Consumption/excretion: Citharexylum spinosum is dispersed to new locations by frugivorous birds.

For ornamental purposes (local): Citharexylum spinosum is spread by humans who cultivate the tree for landscaping.

Management information:

Preventative measures: A Risk Assessment of Citharexylum spinosum for Hawai‘i and other Pacific islands was prepared derived with minor modifications for use in Pacific islands. The result is a score of 7 and a recommendation of: “reject the plant for import (Australia) or species likely to be of high risk (Pacific)”.

Cultural: The public should be informed not to plant C. spinosum.

Physical: If cut and not treated, C. spinosum will certainly grow back.

Chemical: Chemicals will likely play a role in controlling C. spinosum because it grows back when cut to the ground.

Biological: A treehopper Aconophora compressa was released in 1995 in Australia for control of Lantana camara, a weedy species in the same family as C. spinosum. Several populations of A. compressa were found on C. spinosum after their release, and have been damaging the tree and other plants since then.

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