What differentiates legumes from the rest of the angiosperms is the structure of the flower and the fruit or legume.
The flower is zygomorphic and consists in five welded sepals and a dialipetal corolla of five different petals. The top petal is larger than the rest and is called the standard; the two lateral ones, called wings, are below that and envelop the two lower ones, which form the keel and which are slightly welded. As a whole, the flower looks like a butterfly, which is why these plants are also called Papillonaceae.
The stamens, ten in all, are fused to form a tube that surrounds the single unicarpellar, many-seeded pistil.
Legumes are dehiscent nuts that open by a longitudinal suture; they can be elongated, like peas, or short and round like chickpeas. The number of seeds they contain is variable. Legumes are herbaceous and shrubby plants, although they include some tree species. The leaves are compound or simple. Many of them have stipules at the point where the leaf joins the stem.
The bean (Phaseolus vulgaris) is an annual herbaceous plant with climbing stems. The leaves are trifoliate and have two small stipules at the base of the petiole. The flowers, yellowish in color, have a curved keel. They are grown in gardens, on rough ground prepared for the plants to climb. They are harvested green or the pods are left to dry on the plant to collect the seeds after they have dried.
Other legumes of food interest are chickpeas (Cicer), lentils (Lens), fava beans (Vicia) and soybeans (Glycine). There are some that are important as fodder: alfalfa (Medicago) and clover (Trifolium). There are other species that are trees, such as the carob (Ceratonia siliqua), a very characteristic tree of the Mediterranean region.
The Ganxet variety has late plants, with indeterminate and climbing growth, long internodes, dark green leaves and petals and white flowers. The crochet bean has a slightly shiny white, flattened and strongly curled grain. They have pods of 13.6 to 17 cm in length with 3.7 to 5.8 seeds per pod and yields of 36.3 to 51.9 g/plant. The seeds are medium to large (37.3 to 61.9 g/100 seeds), flattened and rounded (hook degree between 1.5 and 2.8 out of 3). Once cooked, the bean has a slightly rough and barely perceptible skin, with a persistent creaminess and an extremely mild flavor. Ganxet beans have been a traditional crop in certain areas of Catalonia since ancient times.