During quarantine I began regularly exploring a protected grassy field near my neighborhood. Earlier this Spring I discovered an abundance of Spiderwort, a plant native to Missouri and North America. Throughout the weeks I have been monitoring the changing landscape and have found a new beauty, the Carolina Horsenettle. The tiny size of the flower, along with its noticeably large anthers that appear almost banana-like, immediately caught my attention.
A close-up of the Horsenettle flower, with its prominent and somewhat comical banana-like anthers.
Characteristics of the Carolina horsenettle (Solanum carolinense)
Family: Solanaceae (nightshades)
While called a nettle, the Horsenettle is an herbaceous perennial plant of the nightshade family, native to the southeastern United States. Examples of nightshade plants include tomatoes, potatoes, bell peppers, jimsonweed and the poisonous belladonna nightshade. Characterized by an alkaloid called solanine, nightshades can be toxic in high concentrations or at the very least, an inflammation-causing irritant. Solanaceae plants include agricultural vegetables that are safe for human consumption, only made edible by an extensive carbohydrate side chain.
Horsenettle can be found across the entire continent, but is noticeably sparse in several locations including Canada. The United States Department of Agriculture has labeled the Carolina horsenettle as a prohibited noxious weed in Arizona, Alaska, Arkansas, California, Hawaii, Iowa and Nevada.
Each Horsenettle flower contains five united petals formed into a star-shape and measures 1″ in diameter. The small flowers can be found in shades ranging from white to purple. Leaves are oblong and oval in shape, containing spines located on its underside. The anthers are large, prominent, and full of bright-yellow pollen.
Flowers bloom from early Summer to early Fall and last a month or so before wilting. After the flowering phase, small tomato-like fruits begin to appear, which are poisonous and potentially fatal to humans. The solanine alkaloids found in nightshade plants can cause an array of symptoms including nausea, vomiting, abdominal pain, diarrhea, and respiratory depression.
Extensive Root System
The plants I observed in the field were approximately 6-12 inches in height, though the Horsenettle plant can grow as tall as 36 inches. However, it is underground that the reach of the plant is truly revealed. The extensive horizontal root system of the Horsenettle can plunge as far as 8 feet into the ground, sprouting taproots along the way. Because of its ability to spread far and wide vegetatively by rhizomes underground, the plant can be difficult to remove and is thus often labeled a noxious weed.
Pollinators & Propagators
Bumblebees are frequent pollinators of the Horsenettle. The unique, oblong shape of the Horsenettle anther allows for easy sonication. Utilizing this method of buzz-pollination, bumblebees rapidly vibrate their thoracic flight muscles to dislodge pollen from the plant’s anthers. A limited selection of birds and smaller mammals that consume the plant’s fruit scatter the seeds via defecation.
A close-up view of a bumblebee’s engorged pollen sac, located on the animal’s hind-quarters.
Though not medicinally used today, people have used Horsenettle to treat epilepsy, asthma, bronchitis, and as a sedative. Other uses of the plant include diuretics and as a method to suppress muscle spasms. Native Americans once used the leaves of the plant to make a throat-soothing tea and as a topical treatment for poison ivy.
Spiny stems and leaves, often found in nettles, can be seen in the image above.
Pictured above: Toxic growing fruits, which resemble tiny tomatoes.
Despite being labeled as toxic and noxious, the Horsenettle plant is a beautiful little plant with pretty, delicate flowers. Hellish nicknames like the Devil’s Tomato, the Apple of Sodom and the Tread-Softly tell us that we have been cautiously avoiding this plant for a long time. With spiny leaves, poisonous fruit and a robust root system that just won’t quit, the Horsenettle is a pest that is likely to stay around.
See more of my Missouri Native Species Collection
Sources: Missouri Department of Conservation, Missouri Botanical Garden, Georgetown University Medical Center, United States Department of Agriculture
Technical: Fujifilm x100V