Stinging nettle is a plant widely known for the irritating sensation it causes upon contact. The common name “nettle” often refers to this specific plant, leading to some confusion about its relationship to a broader plant family. This article clarifies the distinction between “nettle” as a general term and stinging nettle, exploring its characteristics and the science behind its sting.
The Nettle Family and Stinging Nettle
The term “nettle” is frequently used to describe Urtica dioica, commonly known as stinging nettle, which is the most well-known species within the larger nettle family, Urticaceae. This family encompasses approximately 54 genera and 2,625 species of plants found globally, excluding polar regions. While Urtica dioica is the predominant stinging nettle, other species within the Urtica genus also possess stinging hairs. The Urticaceae family includes various plants, some of which do not sting, such as ramie (Boehmeria nivea) and baby tears (Helxine soleiroli). Urtica dioica itself has several subspecies, with most having the characteristic stinging hairs.
Recognizing Stinging Nettle
Identifying Urtica dioica in its natural environment involves observing several key features. This herbaceous perennial plant can grow quite tall, reaching heights of 0.9 to 2 meters (3 to 7 feet), and sometimes up to 3 meters (10 feet). Its soft, green leaves are 3 to 20 centimeters (1 to 6 inches) long, arranged oppositely on an erect, wiry stem.
The leaves are heart-shaped or oval with strongly serrated edges and a pointed tip. The stems are square and covered with bristly hairs. Both the stems and the undersides of the leaves are equipped with fine, hollow stinging hairs, known as trichomes. Stinging nettle grows in areas with moist, fertile, and disturbed ground, such as roadsides, hedgerows, and along stream banks.
Understanding the Stinging Sensation
The irritation experienced from stinging nettle is due to specialized hollow hairs, or trichomes, that act like tiny hypodermic needles. When these fragile, silica-tipped hairs are brushed against, their tips break off, allowing the remaining needle-like structure to pierce the skin. This action injects a cocktail of chemicals into the skin.
The primary chemicals responsible for the immediate stinging, burning, and itching sensation include histamine, acetylcholine, and serotonin. While formic acid was once thought to be the main irritant, it is present in too low a concentration to account for the prolonged effects. The reaction, known as contact urticaria, manifests as raised bumps or hives, accompanied by redness and itching, and can last for several hours or even up to 24 hours.
If stung, it is advisable to avoid rubbing the area for the first 10 minutes to prevent pushing the chemicals deeper into the skin. Washing the affected area with soap and water can help remove chemicals, and applying a cool compress or a dock leaf may provide some relief.