Photographer:Stephen Ausmus Affiliation: USDA Agricultural Research Service Source:www.bugwood.org Copyright: CC BY 3.0
The bottle brush tree (Melaleuca quinquenervia) has many common names such as punktree because of the black coloration on the bark when it has been burned, paperbark, cajeput tree, or melaleuca. It is a perennial evergreen tree that varies in height with environment. In wet or swampy environments it will be 49 to 68 feet tall with maximum heights of 98 feet. Dry environments that experience wind and fire exposure will have bottle brush trees that are 26 to 33 feet tall. The overall appearance of the plant can vary from multi-stemmed to single stemmed with a relatively straight trunk. The branches of juvenile trees are erect and ascending while older trees will have droopy branches. The leaves of bottle brush trees are leathery, 2-5 inches long, and .4-2 inches wide. Dark colored flowers form terminally on the branches covered in spikes. The branch will often continue to grow after the flower has appeared and produce foliage or more flowers on the other side of the old flower.
In its native environment of Australia, the bottle brush tree is valued for its attractiveness to birds and bats. However, in the United States it is considered a pest, and is listed on the federal noxious weeds list. With an ability to grow in aquatic or terrestrial environments, the bottle brush tree can become established in a variety of areas including those that didn't previously have trees. This introduction of trees changes the habitat formerly known by native wildlife. Native vegetation populations are seriously reduced when the bottle brush tree becomes established because of its character to grow in thick monocultures that are nearly impossible to control. Its greatest threat is to the Florida Everglades ecosystem, which faces extreme and possibly irreversible alteration as a result of intrusion by paperbark tree and another troublesome exotic, Brazilian pepper (Schinus terebinthifolius).
Seeds are continuously formed on the bottle brush tree, even from previously damaged portions that are quickly regenerated. Propagation and distribution of the plant occurs via seed production that takes place 2-5 times a year, allowing for 850,000 tiny seeds contained in one capsule. Each branch contains at least one seed capsule, and often will contain more than one due to the ability of branches to grow on the terminal end of the flower after the seed capsule has formed. In response to herbicide, fire, or removal of branches, the bottle brush tree will quickly produce thousands of seeds for rapid dispersal. The parent tree is then able regenerate damaged tissue and branches following the destructive event. In the case of fire, seeds that were quickly released are aided in dispersal because of the fire.
In the early 1900's the bottle brush tree was introduced to the United States as an ornamental tree. Since its introduction, the bottle brush tree has spread and become highly invasive in South Florida, specifically the Everglades where trees did not previously grow. Intentional introduction of the plant has also occurred in Hawaii and Puerto Rico, but the plant has not become invasive to the same degree as areas of Florida. It is currently listed as a federally noxious weed and it is not encouraged to purchase and grow this plant.
Tropical Asia, Australasia, & Pacific-New Caledonia
U.S. Habitat: The bottle brush tree is able to grow in completely aquatic environments, such as the Florida Everglades, or in terrestrial environments with adequate moisture available. Once established, it will invade upland piney woods as well as hardwood bottomlands.
U.S. Present: FL, HI, LA, PR
Melaleuca resembles red bottlebrush (Callistemon citrinus), but the flowers of C. citrinus are red.
Texas Alternatives: include Red mulberry (Morus rubra), Wax myrtle (Morella cerifera), and Mexican plum (Prunus mexicana).
Researchers are working to find effective methods of eradication for the bottle brush tree. Herbicides have been found somewhat effective, but mixes are still being tested. Fire treatment facilitates further spread of the bottle brush tree rather than reducing it, by spreading heat tolerant seeds. Areas in Florida are testing the efficacy of biological control insects, with no highly effective results at this time.
Restoration of areas infested with paperbark tree requires a well-planned, long term commitment to elimination of all paperbark trees from the site and prevention of reinfestation. The age and extent of an infestation, the availability of people and other resources, and the proximity to open water or wetlands will dictate the type of management best suited for each site. Seedlings can be pulled by hand, especially when the soil has dried out some, small to medium-sized trees can be pushed over, and larger trees may be cut. Resprouting will likely occur after cutting or hand- pulling, requiring follow-up removals or treatment with herbicide. Herbicides are usually needed for extensive infestations and mature paperbark trees and may be applied to freshly cut stumps or to girdled trunks. However, as noted previously, herbicide use will cause paperbark tree to release large caches of stored seeds. Biological control may offer some help in management of this aggressive invader. Several species of Australian snout beetles are being released or evaluated by the U.S. Department of Agriculture. The beetles are specific to Melaleuca and feed on its shoots, reducing the plant's ability to reproduce.
USE PESTICIDES WISELY: Always read the entire pesticide label carefully, follow all mixing and application instructions and wear all recommended personal protective gear and clothing.
Contributions from Texas Invasives for this species page are greatly appreciated.
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The Quiet Invasion: A Guide to Invasive Plants of the Galveston Bay Area (www.galvbayinvasives.org). Lisa Gonzalez and Jeff DallaRosa. Houston Advanced Research Center, 2006.