The peanut, or groundnut (Arachis hypogaea) is a species in the legume family Fabaceae native to South America. It is an annual herbaceous plant growing to 30 to 50 cm (1 to 1 1/2 feet) tall. The leaves are opposite, pinnate with four leaflets (two opposite pairs; no terminal leaflet), each leaflet 1 to 7 cm (1/3 to 2.75 inches) long and 1 to 3 cm (1/3 to 1 inch) broad. The flowers are a typical peaflower in shape, 2 to 4 cm (3/4 to one and a half inches) across, yellow with reddish veining. After pollination, the fruit develops into a legume 3 to 7 cm (1 to 2 inches) long containing 1 to 3 (rarely 4) seeds, which forces its way underground to mature. Although a nut in the culinary sense, in the botanical sense the fruit of the peanut is a woody, indehiscent legume or pod and not technically a nut. Peanuts are also known as earthnuts, goobers, goober peas, pindas, jack nuts, pinders, manila nuts and monkey nuts (the last of these is often used to mean the entire pod, not just the seeds). Peanuts are a rich source of proteins (roughly 30 grams per cup after roasting) and Monounsaturated fat. Recent research on peanuts and nuts in general has found anti-oxidants and other chemicals that may provide health benefits.  Peanuts are a significant source of resveratrol, a chemical studied for potential anti-aging effects. Because peanuts are considered an incomplete protein, containing relatively low amounts of the essential amino acids Lysine, Cystine, and Methionine, it is advised to be sure that a diet or meal with peanuts as a staple also include complementary foods such as dairy or whole grain Although many people enjoy foods made with peanuts, some people have severe allergic reactions. For people with peanut allergy, exposure can cause fatal anaphylactic shock. For these individuals, eating a single peanut or just breathing the dust from peanuts can cause a fatal reaction. An allergic reaction also can be triggered by eating foods that have been processed with machines that have previously processed peanuts, making avoiding such foods difficult. A theory of the development of peanut allergy has to do with the way that peanuts are processed in North America versus other countries like China and India. Peanuts are widely eaten in China and India but peanut allergies are almost unheard of there. According to a 2003 study, roasting peanuts, as more commonly done in North America, causes the major peanut allergen Ara h2 to become a stronger inhibitor of the digestive enzyme trypsin, making it more resistant to digestion. Additionally, this allergen has also been shown to protect Ara h1, another major peanut allergen, from digestion - a characteristic further enhanced by roasting.