All three plants—Groundnut, Horse-gram, and Soybean—belong to the pea family, scientifically known as Leguminosae or Fabaceae. This family is characterized by plants that produce legumes (pods containing seeds). Here's a breakdown of each:

Groundnut (Arachis hypogaea):

• Groundnut, also known as peanut, belongs to the Leguminosae family. It produces peanuts, which grow underground in pods, typical of legumes.

• It is part of the subfamily Faboideae, a major division within the pea family.

Horse-gram (Macrotyloma uniflorum):

• Horse-gram is another plant in the Leguminosae family. It is commonly cultivated in tropical regions and is known for its high protein content and use in animal feed and food.

• It belongs to the subfamily Faboideae as well.

Soybean (Glycine max):

• Soybean, one of the most important leguminous crops, also belongs to the Leguminosae family. It is widely grown for its edible beans and oil extraction.

• Soybean is part of the subfamily Faboideae too.

All three plants are legumes, characterized by their pod-like fruit and ability to fix nitrogen from the atmosphere through a symbiotic relationship with bacteria in their root nodules.