Invasive Ornamental Plants in Florida
Invasive Ornamental Plants
Florida has a great sub-tropical climate that allows many fine exotic plants to thrive in our landscapes. Unfortunately, some of these plants are a little to comfortable in Florida and begin to take over sensitive native habitats. The following is a list of ornamental plants that should be avoided in new plantings because of their invasive potential.
In years past, some highly palatable and prolifically fruiting exotic species were planted and promoted by wildlife enthusiasts before their negative effects on the natural world became apparent. Some examples of invasive plants we caution against include Japanese honeysuckle (Lonicera japonica), Chinese privet (Ligustrum sinense), and coral ardisia (Ardisia crenata). Many of the benefits provided by these invasive species could instead be provided by native species. When possible, avoid planting these species and remove them on existing sites if feasible.
Ornamental Invasive Plants in Florida
Albizia julibrissin (Mimosa)
This fast-growing, deciduous tree has a low branching, open, spreading habit and delicate, lacy, almost fern-like foliage. Fragrant, silky, pink puffy pompom blooms, two inches in diameter, appear in abundance from late April to early July creating a spectacular sight. But the tree produces numerous seed pods and harbors insect (webworm) and disease (vascular wilt) problems. Although rather short-lived (10 to 20 years), mimosa is popular for use as a terrace or patio tree for its light, dappled shade and tropical effect. Its deciduous nature allows the warming sun to penetrate during the winter. Read more about Albizia julibrissin here.
Ardisia crenata (coral ardisia)
Coral ardisia, also known as coral berry, spice berry, and scratchthroat, was introduced to Florida in the early 1900’s for ornamental purposes. Since then, it has escaped cultivation, and it is found in hardwood hammocks and other moist, natural-wooded areas and grazing lands. Documented herbarium specimens, or preserved plants, have been collected from 19 western and south-central Florida counties. Coral ardisia is considered invasive by the Florida Exotic Pest Plant Council and the UF/IFAS Assessment. Read more about the invasive nature of this species in this article.
Casuarina equisetfolia (Australian pine)
This evergreen tree is native to Australia, the South Pacific Islands, and Southeast Asia, but it has successfully naturalized in all of Hawaii, Puerto Rico, the Virgin Islands, and in Florida south of Orlando. It has become established and grows vigorously on disturbed sites such as roadsides and filled wetlands, and is commonly seen along coastlines in Florida. Australian pine is salt tolerant and grows well in sandy soil. Thriving in bright, full sunlight, this tree can reach heights of up to 100 feet with a canopy spread of up to 40 feet. A magnifying glass is needed to see the 0.25-inch-long evergreen leaves that press against the 0.03-inch-diameter stems in a whorled or circular pattern. The bark is red-brown to gray and appears to be constantly peeling from the trunk. The inconspicuous male and female flowers occur on the same tree and bloom twice a year in Florida, first in April and then again in June. The small cone-like structures appear in June and December, producing hundreds of thousands of winged seeds that then disperse with the wind or are eaten by foraging animals that digest and then expel the seed at different locations. Australian pine is a category I invasive species in Florida, and its possession, transport, and cultivation are strictly prohibited by the Florida Division of Plant Industry. Find out more about this highly invasive species in this article.
Cinnamomum camphora (camphor tree)
This large, round-canopied, evergreen tree has broad, large-diameter, unusually strong branches and can reach 70 feet in height with a broader spread but is usually 40 to 50 feet with a 40 to 60-foot spread. The glossy green, thin but leathery leaves give off a camphor aroma when crushed and create dense shade. The stems and bark on young branches of Camphor-Tree are bright green, tinged with red when young, maturing into a dark grey-brown, rugged-looking trunk which appears almost black when wet from rain. Trunk and branch structure on older trees appear similar to mature live oaks. The inconspicuous, tiny, yellow flowers are followed by a profusion of small, black berries which can become an annoyance on walks and driveways because they are messy but are quite attractive to wildlife. Fruits will stain cars. Some seeds germinate below the tree and birds can also carry the seed to remote areas where it will germinate. The leaves, twigs, and wood are the commercial source of camphor. Find out more about this species here.
Colocasia esculenta (elephant ear)
Colocasia esculenta is a tropical plant grown primarily for its edible corms, the root vegetables most commonly known as taro. Elephant ear is a large, showy, marginal aquatic plant with heart-shaped, dark green leaves, taro can reach 5 feet tall and is often grown as a summer annual north of Florida. Usually found in aquatic habitats, so only herbicides labeled for aquatic sites can be used. Large corms (underground storage structures) make control very difficult and repeat applications will be necessary.
Dioscorea bulbifera (air potato)
Air potato is an invasive plant species in Florida that should be removed from public and private properties to help protect the state’s natural areas. It can quickly engulf native vegetation in natural areas, climbing high into mature tree canopies. It produces large numbers of bulbils (aerial tubers), which facilitate its spread and make it extremely difficult to eliminate because new plants sprout from even very small bulbils. It invades a variety of habitats including pinelands and hammocks of natural areas. Read more about this odd invasive species here.
Eichhornia crassipes (Water hyacinth)
Water hyacinth is a free-floating aquatic plant that grows throughout the year in southern Florida but undergoes winter dieback in northern parts of the state. The species can survive moderate freezes but requires temperatures above 50°F to produce new growth. The transportation, importation, collection, possession, cultivation, or sale of waterhyacinth (a Class I Prohibited Aquatic Plant) is illegal in Florida, but the species is still occasionally available for purchase from some farmers’ markets, yard sales, aquarium supply stores, aquatic plant nurseries, and Internet sources in other states. Read more about this aquatic pest here.
Lantana camara (Lantana)
Lantana (Lantana camara) is a woody member of the Verbenaceae that is native to the tropical Americas. This plant flowers abundantly throughout much of the growing season and was first introduced in many southern states as a perennial ornamental. Because of the plant’s ornamental nature, many different flower colors exist, but the most common color combinations are red/yellow and purple/white. Lantana is now commonly found in naturalized populations throughout the southeastern United States from Florida to Texas. Lantana is currently one of the top 10 most troublesome weeds in Florida, with documented occurrences in 58 of 67 counties. Although it is still sold as an ornamental, commercial varieties are sterile and considered to be non-invasive. Read more about this species here.
Ligustrum sinense (Chinese privet)
Chinese Privet is an abundant semi-evergreen small tree or large shrub, most commonly found invading the understory of moist areas. One of Florida’s biggest exotic invasive problem shrubs. With small, opposite, thickened leaves, it isn’t likely to be confused with native trees, though young ones can be confused with the native Coralberry (Symphoricarpos orbiculatus), which is a low shrub with thinner leaves. The trunk is usually forked near the base. Bark is a smooth gray with lenticels. The shade under a Chinese Privet is often so dense that almost nothing can grow underneath it. Establishment of privet in many natural areas of Florida has occurred through its escape from cultivation. It is capable of invading natural areas such as floodplain forests and woodlands. The aggressive nature of privets allows for the formation of dense thickets that out compete desirable plants. The amount of seed produced by privet is another mechanism for its prolonged survival. Even though privet is still used in the landscape and available for purchase at garden centers and online distributors, it is an invasive weed and should be treated as such. Read more about this species here.
Lonicera japonica (Japanese honeysuckle)
Japanese honeysuckle is a species of honeysuckle native to eastern Asia including China, Japan and Korea. It is a twining vine able to climb up to 30 feet high or more in trees, with opposite, simple oval leaves 1 to 3 inches long and 0.75–1.25 inches wide. The flowers are double-tongued, opening white and fading to yellow, and sweetly vanilla scented. The fruit is a black spherical berry containing a few seeds. It is an invasive species in a number of countries and states, including Florida. The vines smother young trees and disrupt the natural succession of woodland areas. Use native species of Lonicera in the landscape.
Lygodium microphyllum (Old World climbing fern)
Old World climbing fern plants consist of fronds (up to 90 feet long) that spread along the ground, over shrubs, or climb by twining around other structures, such as trees and other vines. The rhizomes (underground stems) and rachis (main stem of the frond) are dark brown to black and wiry. Leafy branches, referred to as pinnae, develop off the rachis and are 2–5 inches long. Pinnae contain several pairs of either fertile or infertile leaflets known as pinnules. Fertile leaflets are fringed with tiny lobes of enrolled leaf tissue along the leaf margin that cover the reproductive tissues. Infertile leaflets lack these specialized reproductive structures. Old World climbing fern is closely related to Japanese climbing fern (Lygodium japonicum) but can be readily distinguished by pinnae and pinnule characteristics. Japanese climbing fern pinnae are often twice compound, and pinnules are deeply lobed and hairy on the lower surface. Old World climbing fern pinnae are once compound, and pinnules are oblong, generally unlobed, and hairless on the lower surface.
Old World climbing fern climbs into the tree canopy and competes with canopy trees and understory vegetation for light. It can completely engulf Everglade tree islands, pinelands, and cypress swamps, and spreads across open wetland marshes. It can kill mature trees along with their associated epiphytic orchids and bromeliads, and smother understory vegetation, preventing regeneration of the native plant community. As time progresses, a thick mat of old fern material accumulates on the ground, severely altering the habitat. When fire occurs, the fern carries fire into the tree canopy, causing greater damage and transporting fire through wet areas that otherwise present a boundary to the spread of fire. Rare plant species, such as the tropical curlygrass fern (Actinostachys pennula) and thin-leaved vanilla orchid (Vanilla mexicana), are threatened in their last remaining habitats, such as northern Everglade tree islands and coastal bay swamps. However, the highest potential for significant damage to native plant populations is in areas such as Fakahatchee Strand State Preserve, Everglades National Park, and Big Pine Key National Wildlife Refuge, where numerous rare plants occur. Read more about this fern pest here.
Melaleuca quinquenervia (Melaleuca)
This evergreen tree originates from the South Pacific where it is native to Australia, New Guinea, and the Solomon Islands. In the United States it is non-native and invasive and is found in Louisiana and south of central Florida, where it invades a variety of habitat types ranging from wet swamps to dry uplands. Melaleuca grows well in partial shade and can reach heights of up to 100 feet. Leaves are simple and alternate, and can grow to lengths of 4 inches. The grayish green leaves have a narrow lanceolate shape, entire margins, and 5 to 7 parallel veins that run from the tip of the leaf blade down to its base. When the leaves are crushed they release an aroma similar to camphor. The outer bark is whitish and soft, and peels into thin layers, revealing a reddish inner bark. During the spring and summer months, fragrant white flowers bloom in clusters shaped like bottle brushes. Fruits are small (3/8 inch), woody, cylindrical capsules borne in clusters on young branchlets, and each capsule houses between 200 to 300 tiny seeds.
In the early 1900s, this tree was introduced into Florida as an ornamental plant. In the 1930s it was intentionally spread throughout the Everglades area and subsequently began changing the dynamics of this unique ecosystem. It was even planted as a landscape tree in Florida yards until the late 1970s. Today this tree is recognized as a Category I noxious weed by the Florida Exotic Pest Plant Council and is prohibited from being planted in Florida. Find out more about this tree here.
Nandina domestica (heavenly bamboo)
Nandina is an evergreen or semi-evergreen woody shrub that can grow 6 to 8 feet in height. The tri-pinnately compound leaves are alternately arranged. Leaflets are ovate, 1 to 2 inches long while the entire leaf is 10 to 20 inches long. Leaves start out reddish bronze, eventually turning green and then reddish in the fall. The inner bark of nandina is yellow, a characteristic of many plants in the Berberidaceae. Some refer to nandina as bamboo because of the visual similarity between genera. Bamboo however is in the family Poaceae, or the grass family. White flowers are borne in panicles at the end of the stem. Fruit is red and often persists until consumed by birds or other wildlife.
Originally from China and Japan, nandina, or heavenly bamboo, was introduced to the United States in 1804 for use as an ornamental plant. This plant has many uses in the garden as the foliage and fruit are particularly attractive and desirable to homeowners. However its ability to grow tall quickly and reproduce by seed and root fragments becomes a major nuisance for most avid gardeners. Nandina has been placed on the Florida Exotic Pest Plant Council’s invasive list as a Category I species. Nandina has been observed throughout Florida in Gadsden, Leon, Jackson, and Citrus counties, in conservation areas, woodlands, and floodplains.
Even though this invasive is available for sale in the nursery trade, there are cultivars being hybridized that do not produce seed. Read more about it here.
Ruellia brittoniana (Mexican bluebell, wild petunia)
Mexican bluebell is an upright or spreading perennial that is known as a strong grower under adverse conditions (Fig. 1). This 18- to 30-inch-tall plant has light green leaves that are medium in texture. Blue, violet, red or pink flowers appear on this perennial in the spring, summer and fall. These flowers are showy, and their nectar is appealing to various species of butterflies. Plants can grow into small flowering shrubs in the warmest parts of south Florida where freezes do not occur.
Mexican bluebell may be used as ground covers and in perennial borders. They are attractive when massed together or planted in a container where flexible stems droop over the pot.
Place Ruellia in an area of the landscape that receives full to partial shade. These species will grow best in well-drained soils and are very drought and salt tolerant. Ruellia species will be frozen to the ground in the winter but regrowth should occur from the roots.
These plants may be propagated by seed or cuttings. Ruellia can become invasive, as it readily reseeds itself. Read more about it here.
Sapium sebiferum (Chinese tallow)
Chinese tallow is a deciduous tree with a milky sap that commonly grows to 30 ft tall. Leaves are simple, alternate, 1–2.5 inches wide, with broadly rounded bases and tapering to a slender point. Leaf stalks are 1–2 inches long. Small yellow flowers that are borne on spikes to 8 inches long occur in spring. The fruit is a 1/2 inch wide, 3-lobed capsule that turns brown at maturity to reveal 3 dull white seeds. The seeds, which often remain attached to the tree through the winter, resemble popcorn, suggesting the other common name of popcorn tree. Read more about this invasive tree species in this article.
Schinus terebinthifolius (Brazilian pepper)
Brazilian pepper-tree is one of the most aggressive of these non-native invaders which were originally introduced as ornamental plants. Where once there were ecologically productive mangrove communities, now there are pure stands of Brazilian pepper-trees. Scrub and pine flatwood communities are also being affected by this invasion. Nearly all terrestrial ecosystems in central and southern Florida are being encroached upon by the Brazilian pepper-tree. Read more about this pest here.
Solarium viarum (Tropical soda apple)
Tropical soda apple is a serious weed problem in many perennial grass pastures of Florida. Its foliage is unpalatable to livestock and the seed is highly viable — it can infest a pasture or native land within 1 to 2 years. It has been observed in pastures, ditch banks, citrus groves, sugar cane fields, vegetable fields, and rangeland throughout the state and has spread outside of Florida to other southern states. It appears to be restricted to semi-disturbed sites. Find out more about it here.
Wedelia trilobata (Wedelia)
It would be hard to find another groundcover better suited to hot, dry conditions than wedelia. Attractive, glossy, dark green, lobed leaves, rapidly spreading growth habit, and a continuous display of small, bright yellow, daisy-like blooms create a much-favored landscape plant. However, this plant has proven to be moderately invasive in Florida.
Wedelia has a vine-like habit and will grow up into shrubs and trees planted in the bed. When used as a groundcover in and among shrubs, it is a high maintenance plant. It looks best planted in a mass over large areas. Like ivy and other creepers, it will require regular trimming along the edge of the groundcover bed to control its spread. It may be best used as a container plant where it will cascade over the side forming a weeping mound of yellow flowers. It has escaped cultivation in certain regions of south Florida where it proliferates, especially in wet areas. Read more about this invasive ornamental here.
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