• Peanuts are the only legume plant that grows underground.peanuts image by Adkok from Fotolia.com
  
  Legumes make up an essential portion of a healthy diet. Compared to other food groups, legumes have a high nutritional value with a relatively low caloric content. Legumes are characterized by their seed-pod origins and come in a variety of shapes and sizes. Sources of legumes exist within the bean and nut families, with select varieties bred as cultivars.
  
  

Beans

• The legume family includes 19 different varieties of beans, all of which grow into a seed-pod form. Included within this category are the kidney, navy, black and garbanzo beans, as well as lentils and pearl barley. Legumes contain several vitamins and nutrients including magnesium, zinc, iron and proteins. When included in a daily diet, their high nutritional content protects the body and reduces a person's risk of developing chronic conditions like cancer, heart disease and obesity, according to the Net Wellness Consumer Health Information website. Beans have little to no cholesterol and provide a healthy amount of fiber, which works towards maintaining digestive health. Beans grow in different climate regions, depending on the type of bean, and originate from different countries across the world.
  
  

Peanuts

• Peanuts are the only legume plants that grows their seeds underground, according to Palomar College. Peanut plants originated in central South America and quickly migrated to other regions shortly after Columbus' discovery of the New World. Their underground growth results from the downward direction in which the plant's stalk grows after fertilization. The plant's root system produces a rich soil environment by attracting beneficial bacterial organisms which increase the nitrogen content of the soil. As a food source, peanuts have a wide variety of uses in sauces, oils and spreads, as well as in raw form straight out of the pod.
  
  

Cultivars

• Within the many varieties of legumes, certain ones are singled out for their nutritional value or their ability to thrive under variable growth conditions, according to the New World Encyclopedia. These special breeds are known as cultivars. Cultivars are species that have been cultivated to grow under certain environmental conditions. Cultivars retain certain desired characteristics of the original legume, and can be produced through sexual or asexual reproduction methods, which increases their availability within different regions of the world. Examples of cultivar legumes include string beans, snow peas and sugar snap peas. According to Palomar College, soybean legumes are one of the most popular cultivars because of their high protein content, which makes them a staple of vegetarian diet plans.