Shady Invaders: Invasive Trees in Your Garden

 

Large shading trees are a great addition to any Florida homeowner’s landscape. They give nesting opportunities to native wildlife, help prevent erosion, improve air quality, act as a wind break during storms, add property value to a home, and if strategically planted, will even help save on electrical bills by shading the home. However, not all trees come with the same benefits; some come with detrimental effects to Florida’s ecosystems. Once a tree begins to spread, disrupt native ecosystems, and alter landscapes, it starts to become an invasive species. 

Many of Florida’s invasive trees were brought here to be used as ornamental trees by homeowners, community centers, and businesses. As with many invasive plants in Florida, it didn’t take long for these trees to find their way into sensitive native ecosystems. Once invasive trees establish a small population in native ecosystems, they begin to morph the surroundings. If left unchecked, invasive trees can develop into monocultures, pushing out native plants, creating dense thickets, and decreasing biodiversity. These dense populations cause long term damage to the ecosystem and are costly to repair. On average, the state of Florida spends more that $40 million dollars a year on invasive plant management. Reversing the effects of invasive monocultures takes years of practicing responsible land management techniques. These are some of the reasons why preventing initial invasion is so important. Below is a list of common invasive trees used in Florida landscaping, and at the end of this article we've included some alternative options Florida homeowners can replace them with.

Invasive Trees

Australian pine (Casurina equisetifolia):

Native to Australia, the Australian pine was planted in Florida as a windbreak and coastal shade tree in the 1800s. Even though they were planted as a windbreak, their shallow root system has made them one of the worst trees at withstanding strong gusts. These evergreen trees grow to be upward of 100 feet, with wide-spreading and thick foliage. We did a more thorough write up about these trees on a previous invasive species spotlight here. 

Camphor (Cinnamomum camphora)

Native to China and Japan, the camphor tree was introduced to Florida in 1875 as a plantation crop, but was sold mostly as an ornamental when the products of the tree were not profitable. A large shading tree with glossy green leaves and a distinct menthol fragrance. Camphor can still be seen for sale in nurseries and garden centers around Florida. This tree will grow between 40-50 feet tall with foliage spreading out between 50-70 feet. The black berry-like fruit that the camphor trees produce can stain roads, driveways, sidewalks, and even cars and homes. Spread by birds, the camphor seeds flourish when dropped in dry disturbed areas where they don’t have to compete with other shade trees, such as roadsides or infrequently mowed yards. Learn more here.

Carrotwood (Cupaniopsos anacardioides): 

Native to Australia, Indonesia, and Papua New Guinea, carrotwood was first found in Florida in 1955 but didn’t gain popularity as an ornamental tree until the 1970s. This tree has large, lobed, wavy green leaves, and produces three-lobed fruit with a yellow exterior, exposed orange fleshy tissue, and black seeds. Planted mostly along the coast, this tree is invading costal strands, dunes, coastal scrub, pine flatwoods, cypress and mangrove swamps, and freshwater marshes. Learn more here.

Chinese tallow (Triadica sebifera):

Pollinator at English Wikipedia / CC BY-SA (http://creativecommons.org/licenses/by-sa/3.0/)

Native to eastern Asia, it was introduced to the US as an ornamental plant. A deciduous tree measuring up to 52 feet, with large expanding bright green foliage. In spring, it develops long cluster strings of yellow flowers. Then in late summer you can start to see the dull white seeds start to cover these trees. Those seeds are spread by birds and find their way into closed canopy forests, bottomland hardwood forests, lakeshores, and wetlands. Learn more here.

Lead tree (Leucaena leucocephala): 

Aris riyanto / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

Native to Mexico and Central America, this tree was introduced to Florida as an ornamental tree. Lead trees can grow up to 16ft tall and have white flowers formed in clusters. The seed pods are flat, between 4-6 inches long, and start off green but turn brown when mature. Lead tree can be found invading disturbed areas, cleared areas, coastal strands, outskirts of forests, and canopy gaps. It forms dense thickets and displaces native vegetation. Learn more here.

Queen palm (Syagrus romanzoffiana): 

Forest & Kim Starr / CC BY (https://creativecommons.org/licenses/by/3.0)

Native to South America, queen palms were brought to Florida as an ornamental tree and are a common tree of choice for Florida developers and homeowners. Their long fronds, tall stature, and distinguished trunk convey the popular image of living in a tropical climate. However, there are many drawbacks associate with these trees. Not only are the seeds of the queen palm spread widely by birds and mammals but the tree itself has many qualities that make it a poor landscaping option. It is not a self shedding palm, meaning that once the fronds die they will droop down creating an unsightly brown dressing. They are also sensitive to drought and cold weather and are prone to blowing over in strong storms. Learn more here.

Native Alternatives

Seagrape (Coccoloba uvifera):

Melissa McMasters from Memphis, TN, United States / CC BY (https://creativecommons.org/licenses/by/2.0)

 A costal native, this tree is salt tolerant, wind resistant, and thrives in sandy soils. These trees can grow up to 30 feet tall and their leaves, which can grow between 8-12 inches across, provide great privacy and wind protection. When immature the leaves are red in color but as they mature the leaves turn green with red veins. Only the females will produce the grape-like seeds. These seeds are great for local wildlife and are edible by humans as well. These plants prefer full sun, need regular watering only until established, and take well to shaping and pruning. Learn more here.

Live oak (Quercus virginiana): 

Erik Soderstrom / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

Large, expansive, and shady, live oaks make wonderful statement trees and supply native wildlife with food and nesting areas. Some residents won’t like the leaf litter, acorns or pollen that these trees can drop. Live oaks also have very strong root systems that will seek out water sources, so it is important to plant these a good distance away from sidewalks, driveways, pools, houses, and wells. Learn more here.

Southern magnolia (Magnolia grandiflora): 

gailhampshire from Cradley, Malvern, U.K / CC BY (https://creativecommons.org/licenses/by/2.0)

Dense, glossy, green and red foliage provides the perfect backdrop to highlight the beautiful large white blossoms that can grow to be over a foot across. The tree itself has the capability to grow as tall as 80 feet. They prefer full sun and well drained soils. Learn more here.

Loblolly bay (Gordonia lasianthus): 

M.Aurelius / CC0

A medium size evergreen tree, the loblolly bay has shiny foliage and white showy flowers. It prefers partial shade and moist soils but can withstand full sun with sufficient moisture. Suitable to low maintenance landscapes, provided it regularly gets enough water. Learn more here.

Buttonbush (Cephalanthus occidentalis): 

The Cosmonaut / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

This is a shrubby species than can grow up to 20 ft with unique, white flower clusters. Buttonbush will only grow in wet habitats such as swamps, ponds, and stream edges. Learn more here.

Sabal palm (Sabal palmetto): 

Daniel Di Palma / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

The native sabal palm is the state tree of Florida. This fan palm is self shedding, salt tolerant, and weather-resistant. Learn more here.

Royal palm (Roystonea regia): 

Alejandro  Bayer Tamayo from Armenia, Colombia / CC BY-SA (https://creativecommons.org/licenses/by-sa/2.0)

This south Florida and Cuba native is a majestic addition to any landscape. These trees can grow to towering heights with fronds that can exceed 10 feet in length. Buyer beware- if not strategically planted, these trees can dwarf your other landscape plants and even your house by comparison. Once fully mature, the large fronds are heavy, causing damage to anything they may fall on. Best for a very large yard and planted far from houses and fences. Learn more here.

Non-native but non-invasive alternatives

Royal Poinciana (Delonix regia): 

Averette / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

With compound leaves and showy, bright-red flower clusters, this tree is a favorite of homeowners and landscapers all over Florida. Learn more here.

Jacaranda (Jacaranda mimosifolia): 

H. Zell / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

Another compound-leafed, wide-spreading tree, the jacaranda boasts gorgeous flower clusters of a delicate blue-purple hue. Learn more here.

Foxtail palm (Wodyetia bifurcata): 

Krzysztof Ziarnek, Kenraiz / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

This palm tree is attractive and sturdy, and is probably the closest in appearance to the queen palm of all the alternatives. Learn more here.