Unlike many Bible plants, the nettle is common in both Europe and the Middle East and was therefore translated properly in most verses, e.g, Job 30:7, Proverbs 24:30-31, Hosea 9:6, and Zephaniah 2:9. The KJV is more faithful in this regard than some of the more modern translations.
Nettles are weeds that grow in areas of high nitrogen concentration so are most abundant in places where cattle are kept and about habitations. The entire plant is covered with long, highly specialized hairs that can puncture the skin. Each hair is really a miniature hypodermic needle ready to spring into action. At the tip is a lopsided bulb-like structure that is easily broken at a pre-stressed region. With the slightest touch, the tip falls off leaving the sharp point which can easily penetrate skin. At the base of the hair is a reservoir of irritant, believed to be chemically similar to that injected in ant stings, which is under pressure and escapes through the tip into the victim. The result is a minor dermatitis which will go away in most individuals after thirty minutes or so. This dermatitis, known as urticaria, gives the genus its Latin name, Urtica.
Ecologically, nettles grow in areas of high nitrogen as well as around ruins and archeological sites. Many of the pictures of Urtica pilulifera that follow were taken at archeological sites in Jordan. Pilulifera refers to the ball shaped fruits in this species. The seeds are edible but small and literally a pain to harvest!
There are perhaps six references to nettles in the Bible but, like so many plants, it is not always possible to say with certainty that nettles are meant in each place.