At the entrance is a legumes collection, with a numerous group of genera of erbaceous, shrub and tree species, all characterized by the presence of a fruit that takes the name of legume. This family includes, among others, species important for human and animal nutrition, plants useful for soils consolidation and species used for ornamental purposes.

This collection mainly hosts shrubby and tree species, among which there are Laburnum anagyroides Medik (laburnum), Cercis siliquastrum L. (Judas tree), Styphnolobium japonicum (L.) Schott (sophora), Acacia melanoxylon R.Br.(blackwood). Particular is the trunk of Gleditsia triacanthos L. (thorn of Judah) due to the presence of long branched thorns: it is resistant to drought and low temperatures, it is capable of colonizing poor soils, and it can act as a pest.

In the collection there are also three specimens of Ceratonia siliqua L. (carob tree), well acclimatized despite the plant being typical of Mediterranean environments and sensible to intense colds and frosts. Cultivated since Roman times, from which the edible fruit was particularly appreciated, it is now used for human and animal nutrition, and for ornamental and officinal purposes.