The Herbarium celebrates the INTERNATIONAL YEAR OF PULSES 2016
The 68th UN General Assembly declared 2016 the International Year of Pulses. Pulses are the seeds of plants that belong to the family Leguminosae (also known as Fabaceae) and the term “pulses” is limited to crops harvested solely for their dry grain. The fruit in this family is always a pod, although the flowers vary in structure. Flowers are like a bow or a butterfly in the subfamily Papilionoideae (also named Faboideae), the group with most economically important food legumes. In the Caesalpinioideae the flowers are generally wide open and with long stamens. In the Mimosoideae they are like a pom-pom made of many stamens.
|Caesalpinoideae specimen (Berlinia viridicans Baker f.) - COI00001545||Mimosoideae specimen (Acacia farnesiana (L.) Willd.) - COI00064234 & COI00064235|| Papilionoideae specimen (Lupinus luteus L.) - COI00072459|
Leguminosae is one of the most diverse plant families having c. 24,000 species in c. 940 genera. The family is only second to grasses (cereals) as food plants. Recently, India has been the world’s largest importer of pulses, and Canada the largest exporter. The IYP 2016 aims to raise awareness of the nutritional benefits of pulses and of their role in food security, to promote the use of pulses in the food system and to encourage further research and production and a better trade of this commodity.
One of the great advantages of pulses is that they are dried seeds and can be stored for long periods without losing their nutritional value. Storage increases both food availability between harvests and its potential as a cash crop. The most important grains are beans (Phaseolus vulgaris, from S. America), chickpeas (Cicer arietinum, from the Middle East) and peas (Pisum sativum, from Sw Asia and E. Mediterranean) but there are many others such as lentils (Lens culinaris, Middle East), soya (Glycine max, from E Asia), pigeon-pea (Cajanus cajan, from Africa or India), all being of major importance as food and recognized by health organisations as most important sources of protein. The seeds have two large highly nutritious cotyledons. The cotyledons are the first two leaves of the embryo and become so large because they absorb all the endosperm available in the seed. The endosperm is a triploid tissue that results from fertilization and its role is to feed the very young plant at the time of germination, hence its high content in nutrients. Their amount of calories from protein is similar to meat, 20-30 % (37% in soya beans), although with reduced content in the amino acids methionine and cysteine. They contain no cholesterol, no gluten, their glycaemic index is low.
Nevertheless, some chemicals in pulses are limiting factors to their consumption. Raffinose and stachyose are oligosaccharides for which humans have no enzymes and go intact to the intestine where they ferment and produce gases. Also, many edible pulses, particularly red kidney-beans, contain lectins, toxins that cause nausea, diarrhoea and vomiting. They are haemagglutinins, proteins with special affinity for certain sugar molecules in cell membranes that act on blood cells. These lectins are destroyed by vigorous boiling for 10 minutes.
also important as they can have the dual role as food crop and as enhancers of
soil fertility by fixing nitrogen and freeing phosphorous (due to bacteria in
their roots), thus contributing to more sustainable agricultural systems.
In the Coimbra Herbarium only a small part of the Leguminosae are digitised. The project Plant diversity in Angola: a database of the family Leguminosae (http://www.uc.pt/en/herbario_digital/projects) dealt with 4930 specimens in 165 genera and 904 species, all available in the online catalogue.In 2016 till May 2017, COI is running a volunteer programme for students to digitise the Portuguese legumes in the collection.
In Portugal, the native Leguminosae are all in subfamily Faboideae. Till the 16th century, discovery of America and the introduction of news foods, the pulses consumed in Portugal were broad beans (Vicia faba L.), peas (Pisum sativum L. var. sativum), chickpeas (Cicer arietinum L.), lentils (Lens culinaris Medik.), tremoceiro or white lupin (Lupinus albus L.) and chicharo or grass pea (Lathyrus sativus L.).
|Lupinus albus L.: flower, seeds (tremoços); seeds as snack, a moment of relaxation of the COI team!|
white lupin (Lupinus albus L.), is
cultivated in Portugal as inter-cropping farming systems to enhance soil
fertility, also for seed production for the popular snack, tremoços, to have with
very cold beer. The
bitter raw seeds require some preparation for eating as their content in
anticholinergic alkaloids is toxic, but much reduced in modern varieties.
Toxins are removed by leaching in water and then beans are cooked.
|Lathyrus sativus L. (chícharo): flower, fruit, fallow field and dried deeds from COI-Seminarium collection|
Chícharo or grass pea (Lathyrus sativus) originated in Asia. Its major cultivation in the Mediterranean has declined dramatically – but it has all the features to be playing a serious role on resolving many challenges that agriculture faces in this area.
Research emphasizes the potential of this annual crop
as it compares better with other legumes for drought-prone areas being superior
in yield, protein content, nitrogen fixation, tolerance to drought and
salinity. The neurotoxic non-protein amino acid β-ODAP present in L. sativus could be a problem when there
was overconsumption. It is now proven that the plant is harmless to humans and
animals when consumed as part of a balanced diet and cultivars with low β-ODAP
content are now available. Research at the Centre for Functional
Ecology, University of Coimbra, on biotechnological and
biochemistry techniques toward plant breeding in Lathyrus sativus is being carried out led by Jorge Canhoto.
In Portugal, revival is on the go with the supported of local authorities to promote chicharo with yearly gastronomic festivals in the calcareous hills south of Coimbra, where it was a traditional crop for centuries. The plant was also much cultivated in other areas of calcareous soil, in the Algarve and Sintra, near Lisbon. Spain and Italy follow similar trend. In Turkey, the government is supporting the production of Lathyrus sativus for forage.
Caesalpinioideae Cercis siliquastrum
(Judas tree) from the east Mediterranean is an old fashioned colourful street
|Cercis siliquastrum L. - flower. Coimbra street tree||Cercis siliquastrum L. - tree. Coimbra street tree||Cercis siliquastrum L. - fruit. Coimbra street tree|
Ceratonia siliqua (carob
tree), also from the East Mediterranean, has been much cultivated in the
Algarve since introduced there by the Arabs. The trees are long lived and very resistant to dry
climates. Four forms/cultivars are recognised, mulata (most common), de burro, canela
e galhosa. http://faostat3.fao.org/browse/Q/QC/E
| Ceratonia siliqua L. - immatue fruit. Tree at Coimbra Botanic Garden||Ceratonia siliqua L. - mature fruit. Tree at Coimbra Botanic Garden|| Ceratonia siliqua L. specimen - COI00064230|
Portugal is the second top carob-producing country with 23,000 tonnes in 2013
(FAOSTAT–Food and Agriculture Organization of the United Nations Statistics Division; retrieved July 2016). The pod itself is used to produce a powder that is a chocolate replacement in confectionary, especially in traditional recipes in the Algarve. But the main commercial product of the carob tree is extracted from the seeds. This is the locust bean gum (LBG) or carob bean gum, a thickening, water-binding, gel strengthening used in food technology, the E410, and in non-food industries. LBG is a hydrocolloid polysaccharide of the group of the galactomannans, composed of galactose and mannose units. Solutions of LBG are highly viscous at low concentrations; the gum efficiently binds water thus controlling syneresis, i.e. the weeping of liquid from a gel.
|Production of top 5 Carobs producers in 2013|
Throughout Portugal there are also some invader species in the Leguminosae, the most common being: Acacia dealbata, A. longifolia, A. mearnisii, A. melanoxylon, A. pycnantha, A. retinoides and A. saligna, all from Australia.
Once introduced as ornamentals, to stabilise coastal sand-dunes and occasionally for tannin extraction, they are today a major threat to the native vegetation. Robinia pseudoacacia is another legume invader in Portugal. More information about these species may be found at http://invasoras.pt/, a webpage maintained by a research group on invasive plants from the Centre for Functional Ecology, University of Coimbra, and Agrarian School of Coimbra.