Tropical soda apple (Solanum viarum) is a perennial shrub recognized by its thorny nature and distinctive fruit. Native to regions of South America, this plant has spread globally, establishing itself in warm climates, particularly the southeastern United States. This robust shrub typically grows to a height of three to six feet.
Understanding Tropical Soda Apple’s Edibility
Tropical soda apple is not safe for human consumption, primarily due to the presence of solasodine, a toxic glycoalkaloid found throughout the plant, especially concentrated in its fruit. Unripe, green fruits contain particularly high levels of these toxins and should never be consumed. Even as the fruit ripens and turns yellow or orange, the concentration of solasodine, while potentially decreasing, does not reliably diminish to safe levels for humans.
Although wildlife, such as cattle and feral hogs, may consume the ripe fruits and aid in seed dispersal, this does not indicate safety for humans. Ingesting the fruit can lead to adverse health effects, with potential symptoms including stomach upset and loss of appetite. While a lethal dose for humans would reportedly require a large quantity, around 200 fruits, the unpredictable nature of individual reactions makes any consumption dangerous.
The risk of accidental poisoning is further heightened by the plant’s resemblance to other Solanum species, some of which may be edible or have different toxicity profiles. Misidentifying tropical soda apple as a harmless wild berry or a less toxic nightshade could have serious consequences.
How to Identify Tropical Soda Apple
Tropical soda apple is a thorny, multi-branched perennial shrub, typically reaching heights between three and six feet. Its stems are covered with numerous broad-based, white to yellowish prickles, which can measure up to 0.5 to 2 centimeters long. These sharp thorns are also present on the leaves and even on the flower stalks.
The leaves are a distinguishing feature, deeply lobed and resembling oak leaves. They are broadly ovate, measuring four to eight inches long and two to six inches wide, with prominent veins. Both the upper and lower surfaces of the leaves are typically hairy and bear thorns.
Tropical soda apple produces small, white flowers with five petals and yellow anthers, which are characteristic of many plants in the nightshade family. These flowers typically grow in clusters and can be observed year-round, though their production is often heaviest from September to May in some regions.
The fruits are round, globose berries that undergo a distinct color change as they mature. When immature, they are mottled green with lighter green or white streaks. As they ripen, the fruits transition to a yellow or orange color, measuring about 0.75 to 1.5 inches in diameter. Each mature fruit contains a substantial number of seeds, ranging from 200 to 400.
Why Tropical Soda Apple is a Concern
Tropical soda apple is an invasive species, particularly problematic in the southeastern United States, notably Florida. First identified in Florida in 1988, it has since spread rapidly across the region. This plant’s aggressive growth habit allows it to form dense thickets, which outcompete and displace native vegetation, reducing biodiversity in natural areas.
It also threatens agriculture. It invades pastures and agricultural lands, hindering grazing and reducing crop yields. The plant’s numerous prickles can also create physical barriers, restricting the movement of both livestock and wildlife through infested areas. Furthermore, it acts as a host for various plant viruses and pests that can affect commercially important solanaceous crops, such as tomatoes, potatoes, and peppers.
The primary mechanism for the plant’s widespread dispersal is through animals that consume its fruits and then spread the seeds through their droppings. Birds, cattle, feral pigs, raccoons, and deer are common vectors in this process. Additionally, its seeds can be transported through contaminated hay, farm equipment, and manure, contributing to its rapid spread across new territories. Due to its detrimental impacts, tropical soda apple is classified as a Federal Noxious Weed in the U.S. and is listed on various state noxious weed lists.