Native Plants
What is a native plant and what isn’t?
There is significant debate among botanists and ecologists about which plants are native to certain regions and which are introduced. This page is not going to resolve the debate, nor is it intended to. Instead we offer a framework one can use to think about the plants of the Virgin Islands, their origins and their ecological, economic and cultural importance.

To answer the question we need to define the terms “native and “introduced”.

Native. We define native as a plant species that exists in a location without being moved there by humans. Not one individual plant, but the species. This means that the plant has co-existed or even co-evolved with native wildlife over time. Mutualistic relationships with animals frequently occur under these conditions. Examples are insect pollinated flowers and fruit-eating animals that disperse seed. Some plants like the Sandbox tree (Hura crepitans) have large native ranges that span most of the western tropics. Other Virgin Islands natives, such as the orange manjack (Cordia rickseckeri) and Vahl’s boxwood (Buxus vahlii), are found only in Puerto Rico and St. Croix. Even rarer plants that are found in only one place are considered ‘endemic’ to that place. Marron-bacuba (Solanum conocarpum) is endemic to the island of St. John and the St. Croix century plant (Agave eggersiana) is found only in dry parts of St. Croix.

Introduced. Introduced plants are those that humans intentionally or accidentally brought to a new place. It can sometimes be difficult to prove when, where and how this happened, but paleobotanists have become quite good at determining these facts. Introduced plants are often some of our favorite, most beautiful, delicious and useful plants. That is why people bring them along when they travel to new lands. For the most part, being introduced means the plant has not co-evolved with organisms in the ecosystem. Co-evolution occurs over tens of thousands of years while many common introduced plants have been in their new location for only tens or hundreds of years. Because this designation of plants contains so many well know-plants, it is helpful to break it into two groups.

Naturalized. Naturalized plants were originally transported to a new place by humans, but now reproduce on their own without any assistance from us. Some of the Virgin Islands naturalized plants have been here so long they have become part of our culture and history and are considered a natural part of the landscape. The rain tree (Samanea saman) is originally from Central and South America, where it is common. The tibit tree (Albizia lebbek) is native to Asia and India. Today both trees are commonly found along roadsides and in natural forests of the Virgin Islands where they add beauty and diversity. The beloved mango (Mangifera indica) is also originally from Asia, but wild trees are found all over the Virgin Islands (notably, along Creeky Dam Road in St. Croix.) and cultivated trees are found on farms and in yards

Invasive. Invasive plants are introduced species that cause economic harm to humans and ecological harm to the environment. The plants can be introduced intentionally or accidentally. In their new region they either grow or reproduce incredibly quickly and rapidly spread from the original introduction site. In the Virgin Islands, plants have been introduced; intentionally to improve pasture [tan-tan (Leucaena leucocephala)], via seeds that were accidentally introduced in imported hay [casha (Acacia macrocantha)] and intentionally planted as ornamentals [sweet lime (triphasia trifolia)]. In all three cases, the plants grew rapidly, produced large numbers of seeds and spread rapidly. Today, farmers and home-owners must routinely eradicate these plants to keep their populations under control. These three are considered the most problematic, costly, invasive plants in the Virgin Islands.