Legume vs. leguminosa
While the Italian words legume and leguminosa can both be translated as "legume" in English, they are not interchangeable. Legume refers to the edible seed used for food, whereas leguminosa refers to the entire plant from a botanical or agricultural perspective.
Legume
A2This is the common, everyday word for the edible seeds of a leguminous plant. It is a masculine noun (plural: legumi) used almost exclusively in a culinary or nutritional context, referring to the food you buy, cook, and eat, like beans, lentils, peas, or chickpeas.
La zuppa di legumi è un piatto molto nutriente per l'inverno.
(Legume soup is a very nutritious dish for the winter.)
I ceci sono il mio legume preferito per fare l'hummus.
(Chickpeas are my favorite legume for making hummus.)
Un nutrizionista consiglia di mangiare legumi più volte a settimana.
(A nutritionist advises eating legumes several times a week.)
Ho comprato un barattolo di fagioli, un legume molto versatile in cucina.
(I bought a can of beans, a very versatile legume in the kitchen.)
Le lenticchie sono un legume che cuoce abbastanza in fretta.
(Lentils are a legume that cooks relatively quickly.)
Leguminosa
B2This is a more scientific or technical term that refers to the entire plant belonging to the Leguminosae family (also known as Fabaceae). It is a feminine noun (plural: leguminose) used in the context of botany, agriculture, or gardening to describe the plant itself, including its roots, stem, leaves, and pods.
Il trifoglio è una leguminosa che arricchisce il terreno di azoto.
(Clover is a leguminous plant that enriches the soil with nitrogen.)
In agricoltura biologica si usa spesso una leguminosa per la rotazione delle colture.
(In organic farming, a leguminous plant is often used for crop rotation.)
La soia è una pianta leguminosa di grande importanza economica globale.
(Soy is a leguminous plant of great global economic importance.)
Il professore di botanica ha descritto il ciclo di vita di una leguminosa.
(The botany professor described the life cycle of a leguminous plant.)
L'erba medica è una leguminosa coltivata principalmente come foraggio per animali.
(Alfalfa is a leguminous plant grown mainly as animal fodder.)
Summary
In essence, you eat a legume (the seed), while a farmer or botanist cultivates or studies a leguminosa (the plant). A simple way to remember the difference is to think of an apple versus an apple tree. You use legume in the kitchen or at the grocery store, and leguminosa when talking about farming or plant science.