LEGUMES (FABACEAE): CHARACTERISTICS, HABITAT, CULTIVATION, USES - BIOLOGY - 2025

The legumes (Fabaceae) are a taxonomic family of herbaceous plants, shrubs or trees, perennials and annuals, belonging to the Fabales order. They constitute a group of cosmopolitan distribution that are easily recognized by the typical fruit -legumbre- and the compound leaves with a laminar stipula.

Of the known angiosperms, the Fabaceae family is one of the most numerous along with the Asteraceae and Orchidaceae. In fact, approximately 730 genera and more than 19,500 species have now been described and identified, several of economic importance.

Variety of legumes. Source: pixabay.com

Within the Fabaceous family, three subfamilies with close evolutionary relationships are distinguished: Caesalpinioideae, Mimosoideae and Papilionoideae or Faboideae. These subfamilies constitute a related group with particular characteristics: compound leaves, nodules associated with nitrifying bacteria, and single-skinned dried fruit or legume.

Most fabaceae are adapted to temperate climates, however, there are species acclimated to warm conditions. For example, peas and broad beans are adapted to cold climates; on the other hand, beans, beans and green soybeans in hot climates.

The cultivation of legumes worldwide is of great relevance for human nutrition and soil regeneration. The grains of most species have a high protein content, being an accessible and low-cost nutrient.

In addition, legumes have the property of fixing atmospheric nitrogen to the soil in the roots and transferring it to the soil. Subsequently, this nitrogen assimilated by the soil serves as a nutrient source for the same legumes or other species grown in association.

In sustainable or regenerative production, these plants constitute an essential element to improve the supply of nutrients to the soil. Likewise, the abundant flowering allows to attract pollinating insects, increasing the biodiversity of agricultural ecosystems.

General characteristics

Morphology

Legumes are herbaceous or woody, climbing and fickle herbs and vines, some are shrubs or semi-woody trees. The leaves are generally compound, occasionally simple, alternate and stipulate, frequently presenting small stipelas at the point of insertion of the leaflets.

The hermaphroditic, regular -actinomorphic- and irregular -zygomorphic- flowers are arranged in terminal or axillary inflorescences in the form of spikes, glomeruli, panicles or racemes. The calyx of the flower has five sepals welded together and a suitable corolla with five modified petals.

Legume pods. Source: jacilluch

The numerous stamens, never less than five, are monadelphous, didelphid, and free; the anthers have two dehiscent theca or an apical pore. The pistils are unicarpelar or unilocular with parietal placentation through the ventral suture; sessile ovaries, superb or stipe.

The fruit is a dehiscent legume through the midrib of the carpelar junction, sometimes follicular or with various modifications. The seeds are kidney-shaped with a thick testa, two cotyledons with high nutritional content, and a prominent micropyle.

Taxonomy

• Kingdom: Plantae
• Division: Angiospermae
• Class: Eudicotyledoneae
• Order: Fabales
• Family: Fabaceae Lindley (= Leguminosae Jussieu, nom. Cons.)

Phylogeny

Mimosoids

Trees or shrubs, sometimes grasses, bipinnate leaves, occasionally pinnate or small phyllodes. They comprise 82 genera and approximately 3,300 species in tropical or subtropical regions. They comprise five tribes: Acacieae, Mimoseae, Ingeae, Parkieae, and Mimozygantheae.

Mimosoideae. Source: Diego7864

Papilionoideae or faboideae

Trees, shrubs or vines, pinnate or digitate leaves, often trifoliate or unifolide, but never bipinnate. They comprise 476 genera and 13,860 species, located on all continents with the exception of the Arctic regions. It includes most of the legumes used as food and forage.

Papilionoideae, Source: Ton Rulkens from Mozambique

Caesalpinioideae

Trees, subshrubs or climbing grasses, the leaves are bipinnate or pinnate. They encompass 160 genera and approximately 1,900 species. They comprise four tribes: Cassieae, Cercideae, Caesalpinieae, and Detarieae.

Caesalpinioideae. Source: gailhampshire from Cradley, Malvern, UK

Habitat and distribution

The archaeological evidences have allowed to determine that the fabaceae originated more than 60 million years ago, during the Cretaceous. However, its diversification and proliferation occurred 38-54 million years ago, during the Eocene.

Indeed, it has been possible to determine that the first group of fabaceae to evolve from primitive plants is the group Caesalpinioideae, from which the Mimosoideae and later the Faboideae evolved, the latter being the most recent.

Fabaceae are located throughout the globe, they have a cosmopolitan distribution. In fact, they are located from the equatorial regions to latitudes near the poles, in both warm and temperate climates.

The groups of Caesalpinioideae and Mimosoideae, which are arboreal species, are adapted to tropical and subtropical conditions. While the Papilionoideae or Faboideae, of herbaceous and shrubby bearing, are widely distributed in temperate or extratropical zones.

On the European continent, fabaceae are represented by approximately 70 genera and about 850 species. In the Iberian Peninsula, about 50 genera and about 400 species adapted and widely cultivated in agricultural areas have been recorded.

Legumes particularly require a warm or temperate climate. However, the great diversity of varieties and cultivars has allowed them to adapt to various climatic conditions.

Culture

The steps required to establish a legume crop are listed below, using the bean crop (Phaseolus vulgaris L.) as an example.

Land preparation

Before sowing, it is essential to mechanize the land to ensure the destruction of weeds, incorporation of organic material and aeration of the land. According to the soil analysis, a suitable fertilizer formulation must be incorporated. This practice is also followed in cultivation on terraces.

Phaseolus grains. Source: pixabay.com

Sowing

Sowing is done in rows, covering the seeds with 2-3 cm of soil; the seed is previously disinfected and protected with insecticides and fungicides.

Under suitable environmental conditions and timely irrigation, seed germination occurs between 7-20 days.

Tutored

In the case of the bean, tutoring is essential to achieve vertical growth and form a homogeneous plant network. Tutoring consists of placing a network of threads through timbers along the row of the crop.

In some regions, the cultivation of beans is associated with the cultivation of corn (Zea mays), in order for the bean to grow on and around the corn stalks.

Maintenance works

Leafless

In long-cycle cultivation, the desiccated allows the cultivation to be enhanced when several harvests have already been carried out. This practice allows to improve the production and quality of the pods, reducing the presence of diseases by improving the ventilation of the crop.

Fertiirrigation

The cultivation of beans requires frequent watering, which depends on the physiological conditions of the plant and the edaphoclimatic characteristics of the terrain. It is recommended to water before sowing, during sowing before germination, and during the development of the crop, mainly in flowering and fruiting.

The incorporation of micronutrients in irrigation water is important when nutritional deficiencies are detected in the crop. However, excess moisture can lead to chlorosis, reduction of production until loss of harvest.

Harvest

The harvest or collection is carried out manually, taking into account the physiological maturity of the seed to increase commercial yield. Very tender or dry pods affect the quality of the crop.

The frequency of harvesting takes place around 7-12 days. In low-growing varieties, harvesting can last between 2-3 months and in climbing cultivars between 65-95 days.

Applications

Grain legumes

The importance of these species lies in the nutritional properties of the seeds, which are used for human or animal nutrition. Likewise, the grains are used as green manure, silage or forage.

For human consumption, beans (Phaseolus sp.), Lentils (Lens culinaris); for animal feed alfalfa (Medicago sativa), clovers (Trifolium sp.). As oilseeds, soybeans (Glycine max) and peanuts (Arachis hypogea); as green manures or silage Cicer sp and Pisum sativum.

Alfalfa (Medicago sativa). Source: pixabay.com

Forage legumes

Plants from which both leaves and stems are used, as pods and seeds for animal feed. Forage legumes associated with grass crops or alone are a source of protein for cattle or sheep.

Among the main forage crops are alfalfa (Medicago sativa), corniculated lotus (Lotus corniculatus) and vetch (Vicia sativa).

Vetch (Vicia sativa). Source: Alvesgaspar

Ornamental legumes

There are various species of legumes used as ornamentals in parks and gardens. There is a great variety of herbaceous and arboreal species with great morphological and floristic diversity, perfect for commercialization as ornamentals.

Among the main ornamental fabaceae we can mention the gallomba or scent broom (Spartium junceum) and the false acacia (Robinia pseudoacacia).

Gallomba (Spartium junceum), Source: A. Barra

Other apps

The legume has various applications, as producers of resins or rubber and as honey plants. Likewise, as a source of pigments, phenols, flavonoids or tannins for the dry cleaning industry.

As a source of resin and gums, legumes are of great importance for the food, cosmetic, pharmaceutical and textile industries. Among the main gum-producing species are the dye broom (Genista tinctoria) and licorice (Glycyrrhiza glabra).

Licorice (Glycyrrhiza glabra). Source: Raffi Kojian

Diseases

Ash or powdery mildew (

The main symptoms are whitish powdery spots on the whole plant, mainly the foliar area. The affected stems and leaves turn yellowish and dry.

Gray rot (

The damage occurs at the level of the neck of the plant causing the so-called damping-off rot. The foliar area and the flowers show brown lesions. The fruits exhibit a soft rot.

White rot (

The seedlings present damping-off, which manifests as a watery soft rot without a bad smell that later dries up. Generally, the stems and leaves of the plant become infected, often causing the death of the plant.

Neck and root rot (

At the neck level there is strangulation and rot, as well as at the height of the root system. The disease is often confused with other pathogens. It is a disease of rapid incidence, being caused by non-disinfected substrates, wind or contaminated irrigation water.

Common rust (

Yellowish spots are observed on the upper part of the leaves and a parallel brown spot flush with the underside. It occurs in areas with an average temperature of 21º C. The attack can also appear on the pods, significantly reducing the quality of the crop.

Soft rot (

Disease caused by a polyphagous bacterium that penetrates through the medullary tissues, causing watery rots with an unpleasant odor. It causes blackish spots on the neck and stem of the plant. It occurs in areas with high relative humidity and temperatures between 25-35º C.

Common mosaic virus (BCMV)

Virus that causes light green or dark green spots on the leaves, associated with reddish bumps. The virus is transmitted by the aphids Acyrthosiphon pisum, Aphis fabae, Macrosiphum eforbiae, and Myzus persicae.

Representative species

Fabaceae -leguminous- are an important source of nutrients for human and animal nutrition, mainly due to their high protein content. The following group constitutes the most representative legumes and some of their characteristics.

Alfalfa (

Alfalfa is a species used for animal consumption as a food and forage supplement. The seeds contain a high content of Vitamins A, B, C, D, E, F and K. For human consumption the seeds -flour- or sprouts are used.

Peanut or peanut (

Plant native to America that is characterized because its fruits grow under the ground at the root level. Its fruits contain vitamin B ₃, proteins and antioxidants. It is consumed fresh, toasted, as jam or stew.

Groundnut or groundnut (Arachis hypogaea). Source: pixabay.com

Bean (

Plant native to Mexico, it has been consumed in a traditional way for generations, being one of the traditional crops of the Milpa. There have been approximately 10 thousand varieties of Creole beans worldwide. Bean seeds are rich in vitamin B ₁, protein, phosphorus, iron, magnesium, and manganese.

Chickpea (

Legume native to the Mediterranean, its grains contain vitamins A, B ₁, B ₂, B ₆, C and E, as well as calcium, sodium and potassium. In Mexico it is consumed in soups, stews and nopales; In the Middle East, hummus is a traditional chickpea-based dish.

Chickpea (Cicer arietinum). Source: pixabay.com

Bean (

Grain native to the Middle East and North Africa and the Middle East. The large, soft-colored beans with thick pods are rich in B vitamins, fiber, and calcium.

Huizache (

The huizache is a medium-sized tree plant that is located in warm regions of Mexico. It is a plant that contributes to the protection and nutrition of the soil, it also provides shelter for various animal species. It is not for human consumption.

Huizache (Acacia farnesiana). Source: Mike

Mezquite (

Tree plant native to Mexico, it develops in xerophilic areas and with low rainfall. It reaches 9 m in height and is characterized by its thorns at the height of the branches. The pods are high in protein and carbohydrates and are used for human consumption or as forage.

Lentil (

Cosmopolitan crop with wide edaphoclimatic adaptation and very resistant to drought. Its grains are a source of iron, magnesium, calcium, phosphorus, zinc, protein and vitamins B ₁, B ₃ and B ₆. There are multiple varieties, the most common being brown or brown, being widely consumed in stews and soups.

Lentil (Lens culinaris). Source: pixabay.com

Clover (

Small legume used as forage and nutrient supply to the soil. Fast-growing, it is associated with forage cultivation, being resistant to drought. It is not for human consumption.

References

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2. Duno de Stefano, Rodrigo & Cetzal-Ix, William (2016) Fabaceae (Leguminosae) in the Yucatan Peninsula, Mexico. From the CICY Herbarium 8: 111–116. Yucatan Scientific Research Center, AC ISSN: 2395-8790.
3. Fabaceae: Rosidae - Fabales - Fabaceae (2015) Botanical Consultation Guide II. Faculty of Exact and Natural Sciences and Surveying (UNNE)
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7. Olvera-Luna, AR, Gama-López, S., & Delgado-Salinas, A. (1993). Flora of the Tehuacán-Cuicatlán valley: Fabaceae tribe Aeschynomeneae (Vol. 107). National Autonomous University of Mexico, Institute of Biology.
8. Peralta, E., Murillo, A., Caicedo, C., Pinzón, J. and Rivera, M. (1998) Legume Agricultural Manual. National Legume Program (PRONALEG) Quito, Ecuador.
9. Reynoso, Verónica (2016) Legumes, Regeneration for the Soil. Recovered in: viaorganica.org
10. Rodríguez-Riaño, T., Ortega Olivencia, A. and Devesa, JA (1999) Floral biology in Fabaceae. Real Jardin Botanico, CSIC. Madrid Spain. ISBN: 84-00-07823-3.