As a legume, the peanut belongs to the botanical family Fabaceae; this is also known as Leguminosae, and commonly known as the bean, or pea, family. Peanuts are similar in taste and nutritional profile to tree nuts such as walnuts and almonds, and as a culinary nut are often served in similar ways in Western cuisines. The botanical definition of a "nut" is a fruit whose ovary wall becomes hard at maturity. Peanuts are an especially good source of healthful fats, protein, and fiber. They also contain plenty of potassium, phosphorous, magnesium, and B vitamins. Despite being high in calories, peanuts are nutrient-rich and low in carbohydrates.