Ground bean

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Ground bean
Order : Fabales (Fabales)
Family : Legumes (Fabaceae)
Subfamily : Butterflies (Faboideae)
Tribe : Phaseoleae
Genre : Macrotyloma
Type : Ground bean
Scientific name
Macrotyloma geocarpum
( Harms ) Maréchal & Baudet

The Erdbohne ( Macrotyloma geocarpum ), also Kandelabohne called, is a plant from the genus Macrotyloma in the subfamily Schmetterlingsblütler (Faboideae) within the family of the Leguminosae (Fabaceae). This crop is closely related to a number of other crops called " beans ", particularly the Indian horse bean ( Macrotyloma uniflorum ). The ground bean probably originated in the savannahs of West Africa and is grown less and less often, usually for personal use.

Description and ecology

Macrotyloma geocarpum grows as an annual herbaceous plant and reaches heights of 25 to 30 centimeters. A few days after sowing, epigey germination takes place . A strong taproot is formed. The hairy stems can grow upright on their own or spread as so-called "runner types" lying down. Lower stems form many roots at the nodes, on which there are also root nodules.

The cotyledons quickly fall ( cotyledons from), and there are formed one or two pairs of lances primary leaves. The alternate arranged leaves are divided into petiole and leaf blade. The petioles are up to 25 centimeters long and stand upright. The leaves are threefold. The hairy stalked pinnate leaves are ovate to obovate and up to 8 centimeters long. There are smaller stipules, stipples on the individual leaflets.

The first small inflorescences are formed in the leaf axils just four to six weeks after sowing. The more or less hairy inflorescence stem ends in a thickening. There are only two short-stalked flowers together in an inflorescence . The hermaphrodite, almost sessile butterfly flowers are zygomorphic and five-fold with a double flower envelope . The five hairy sepals are fused into a short and wide calyx, which ends in five unequal, pointed calyx teeth. The five petals are light yellow or ivory to purple-colored. The stylus, which is hairy on the inside in the upper area, has a pointed end and the small scar is on the side under its pointed end. There are 10 stamens, only one of which is free. Self-fertilization takes place and about two days later the flower stalks extend geotropically downwards until the upper ovary reaches the ground and penetrates 1 to 2 centimeters into the soil.

Above ground lying legumes long remain green. Unterirsche legumes are pale in color and remain thin like parchment until ripe. The fruits ripen in the ground, so it is a geocarpe = ground-fruited legume , like the peanut ( Arachis hypogaea ) or the Bambara peanut ( Vigna subterranea ) and, like these, are on a carpophore , hence the common names such as peanuts and the specific epithet geocarpum . The subterranean, thin-skinned, pale and slightly reticulated legumes consist of two to three limbs or segments and are 1.5 to 3.0 centimeters long. There is one seed in each segment, so there are two to three seeds in each legume. The smooth seeds are 8 to 12 millimeters long, 4 to 7 millimeters wide and 2 to 3 millimeters thick, bean-like to egg-shaped and slightly flattened. The seed coat is solid white to brown or black or speckled. The sunken, point-shaped navel ( hilum ) is white and surrounded by a triangular dark-colored spot (eye). The thousand grain weight is between 50 and 150 grams. The seeds mature about six to nine weeks after fertilization.

The number of chromosomes is 2n = 20.


The ground bean is a tropical plant with high temperature and water requirements.

The ground bean is considered tasty and is often harvested in an unripe form. The protein content of the seeds (20 percent) is relatively high, with only a low fat content (less than 2 percent).

The seeds are eaten green or when ripe. Because of its pleasant taste, the peanut is preferred to the peanut or Bambara peanut in some areas. The ripe seeds are often peeled from the legumes in a wooden mortar and the grain is cleaned by wind sifters ( winnowing ). Undamaged grains can be mixed with wood ash and stored for 2 years without losing their ability to germinate. Cooked green or ripe seeds are eaten as a porridge. The seeds are used to grind flour, which is used to prepare pastries and other dishes. The seeds of the ground bean are roasted with salt.

The peanut has good nutritional value with a high raw protein content. When their mother dies, the children of the Sisaala in Ghana receive the bean as their only food during the period of mourning.

The ground bean is used in folk medicine. A brew from the seeds is used against diarrhea. Crushed seeds mixed with water or local beer are used as emetics for poisoning.

All parts of the plant can be used as fodder, for example grazed in the field.

Distribution, origin and endangerment

The area of ​​origin of the pea bean lies in the damp to semi-arid savannah areas of West Africa . The cultivation takes place from Senegal to northern Nigeria , with a focus on northern Ghana . A cultivation in Madagascar is reported. However, it can generally be stated that cultivation is declining and is mainly operated for self-sufficiency.

Wild seeds found in Cameroon and the Central African Republic were collected in 2010 and stored by the Millennium Seed Bank Project using the “ex situ conservation” method. The location of the collected specimens is in dry tree savannah with Combretum , Boswellia and Gardenia species. The current area is larger than 20,000 km 2 . In the IUCN's Red List of Endangered Species , Macrotyloma geocarpum is considered a “Least Concern” = “not endangered” because the populations are stable.


It was first described in 1908 by Hermann August Theodor Harms under the name ( Basionym ) Kerstingiella geocarpa in reports of the German Botanical Society , Volume 26 A, p. 230, plate 3. The new combination to Macrotyloma geocarpum (Harms) Maréchal & Baudet was made in 1977 by Robert Joseph Jean-Marie Maréchal and Jean C. Baudet published in Bulletin du Jardin Botanique National de Belgique , Volume 47, 1-2, p. 50.

Maréchal & Baudet published two varieties in 1977 :

  • Macrotyloma geocarpum (Harms) Marechal & Baudet var. Geocarpum
  • Macrotyloma geocarpum var. Tisserantii (Pellegr.) Maréchal & Baudet ( Syn .: Kerstingiella tisserantii Pellegr. ); in Cameroon and the Central African Republic , smaller short-stemmed leaves, smaller seeds. Possibly also a species of their own.

See also


Individual evidence

  1. a b Macrotyloma geocarpum in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved January 28, 2014.
  2. a b c d e f g h i j k Walter H. Schuster, Joachim Alkämper, Richard Marquard, Adolf Stählin: Legumes for grain use: Grain legumes of the world. Justus Liebig University Giessen, 1998; Joachim Alkämper: Ground bean (Macrotyloma geocarpum (Harms) Maréchal et Baudet) .
  3. a b c d data sheet at PROTA4u .
  4. Macrotyloma geocarpum in the endangered Red List species the IUCN 2013 Posted by: C. Hilton-Taylor, 2012. Retrieved on February 28, 2014 ..
  5. Harms scanned in 1908 at .
  6. Macrotyloma geocarpum at Missouri Botanical Garden, St. Louis, accessed January 28, 2014.

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