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Questions and Answers
Which family does Eragrostis tef belong to?
What type of plant is Eragrostis tef classified as?
Where was Eragrostis tef first domesticated?
What part of the Eragrostis tef plant is primarily utilized?
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In what form is the seed of Eragrostis tef primarily processed for utilization?
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Which family does Eruca vesicaria belong to?
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What region is Eruca vesicaria native to?
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Which part of the Eruca vesicaria plant is primarily used for food?
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How is Eruca vesicaria typically prepared for consumption?
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What was a major limitation of early artificial classification systems?
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Which characteristic defines the binomial system introduced by Carl Linnaeus?
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During which period did significant developments in herbal manuscripts occur due to the invention of the printing press?
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What was one of the issues related to common names in plant classification?
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What was a key feature of Theophrastus's plant classification system?
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What is one primary incentive for human populations to transition from a nomadic lifestyle to settled agriculture?
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How did the practice of plant domestication affect human population dynamics?
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What role did hunter-gatherers play in the ecosystem according to the content?
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What change in human settlement can be linked to the advent of agriculture?
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Which of the following was likely NOT a factor that precipitated the shift to agriculture?
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What is the primary carbohydrate source found in cereal grains?
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Which process led to the development of hexaploid bread wheat?
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What was one of the first methods used by ancient cultures to prepare cereal grains?
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What type of fruit is a caryopsis, which is characteristic of cereal grains?
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What was the final chromosome number resulting from the backcrossing of tetraploid wheat?
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Which statement accurately describes the pericarp of a fruit?
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How are fruits classified based on the ovary position in relation to the flower?
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Which example correctly represents a fleshy fruit?
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What defines an aggregate fruit?
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What is a common feature of the Rose family of plants?
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Which type of fruit is produced by members of the subfamily Maloidae?
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What characterizes the aggregate fruit of the genus Rubus?
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Which fruit type is NOT produced by the economically important members of the subfamily Prunoidae?
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In the classification of the fruit types, which of the following is true about strawberries in the genus Fragaria?
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What is the primary inedible part of a drupe produced by Prunus species?
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What is the primary protein content of dried kidney beans?
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Which of the following describes the asymmetrical shape of legumes?
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What benefit do legumes provide to the soil as they decompose?
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Which genus of bacteria is associated with nitrogen-fixing root nodules in legumes?
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Which of the following characteristics does not typically apply to legumes?
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Study Notes
Botanical Information
- Eragrostis tef, commonly known as teff, belongs to the Poaceae family, which includes grasses.
- Teff is an herbaceous annual plant.
- It is native to the Ethiopian highlands.
History as a Food Plant
- Teff was first domesticated in the Ethiopian highlands.
- It is most widely grown in Ethiopia.
Utilization
- The seed of teff is used as a grain.
- Teff is processed by being ground into flour.
- Teff flour is used to make injera, a flatbread that is a staple food in Ethiopia.
- Teff flour is also used to make other foods, such as pasta, porridge, and cakes.
Botanical Information
- Eruca vesicaria, commonly known as arugula, belongs to the Brassicaceae family.
- It is a herbaceous annual.
- Arugula originated in the Mediterranean region and is now naturalized in many parts of the world.
Utilization
- The leaves of the arugula plant are consumed as a food.
- Arugula is typically eaten raw in salads, sandwiches, and as a garnish. It can also be cooked, but its flavor is milder when cooked.
History of Plant Classification
- Plant classification, grouping organisms based on similarities, has been practiced since Ancient Greek times.
- Early classification systems were based on superficial similarities, such as medicinal properties.
- Theophrastus, a disciple of Aristotle, developed the first systematic plant classification around 2300 years ago, identifying key characteristics and recognizing plant families like Pea, Grass, Sunflower, and Mustard.
- The Age of Herbals (1470-1670) saw the expansion of early works with illustrations and medicinal properties.
- Common names posed communication problems, leading to the development of a Latin-based system of nomenclature.
- Carl Linnaeus simplified the polynomial nomenclature with the binomial system in Species Plantarum (1753), which is still used today.
- Binomial nomenclature uses a generic name and a species epithet, e.g., Picea glauca for white spruce.
- The system follows rules from the International Code of Botanical Nomenclature, including capitalization, italicization, and authority designations.
Plant Species and the Biological Species Concept
- The biological species concept defines a species as a group of interbreeding individuals.
- This concept is difficult to apply to plants due to:
- Spatial separation of populations, making interbreeding difficult.
- Formation of fertile hybrids between different species.
- Some species reproduce asexually, undermining the interbreeding requirement.
- Plant taxonomists rely heavily on morphological form to classify and describe species.
Challenges to Morphological Based Classification
- Morphological form is influenced by environmental conditions, making it sometimes unreliable for classification.
- Evolution constantly alters morphological form, resulting in diverse forms and adaptations.
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Examples of morphological diversity:
- Potentilla plants are sensitive to light levels.
- Fruits and vegetables are different in domestication compared to their wild counterparts.
- Rafflesia's large flower, with a "corpse" smell, attracts insects.
- South African Parasitic Plant siphons nutrients from other plants.
- Titan Arum is a tall flowering plant.
- Duckweed, with its small size, facilitates rapid spread.
- Victoria Water Lily maximizes surface area for light absorption.
- Baobab trees have large, thick trunks.
- Socotra Dragon Trees can grow up to 12 meters.
- Giant Senecio, on Mt. Kilimanjaro, survives in foggy weather.
- Azarella compacta, a cushion-like plant in the South American Andes.
- Colocynth, found in North African deserts.
Evolutionary Relationships and Phylogenetic Classification
- Phenetic classification systems are based on morphology, emphasizing conservative characters that are less influenced by environmental conditions.
- Phylogenetic classification emphasizes evolutionary relationships, requiring information on ancestral relationships and identifying primitive and advanced characters..
- Charles Darwin’s Origin of Species (1859) led to increased interest in phylogenetic classification.
- Two competing theories regarding flowering plant evolution:
- Engler: Early evolved flowers were small, simple, and wind-pollinated.
- Hooker: Early evolved flowers were large with numerous floral parts.
- The Hooker system is currently accepted, with further refinements based on molecular data.
Flowering Plants: Monocots and Eudicots
- Flowering plants (angiosperms) are traditionally classified into two major groups: monocots and eudicots.
- Monocots have a single cotyledon (seed leaf), while eudicots have two cotyledons.
- Other distinguishing features:
- Monocots: herbaceous, three or multiples of floral parts, linear leaves with parallel veins, fibrous root system.
- Eudicots: herbaceous or woody, four or five or multiples of floral parts, broad, net-veined leaves, taproot system.
- Recent genetic investigations have revealed a third group, magnoliid Angiosperms, which evolved before monocots and eudicots.
Early History of Plants and People
- Domestication of plants is believed to have begun around 10,000 years ago.
- Prior to domestication, humans lived as hunter-gatherers, collecting food from the wild.
- Hunter-gatherer populations were kept below the environment's carrying capacity.
- Hunter-gatherers required a nomadic lifestyle due to the seasonal nature of food.
- Humans, being omnivores, relied on plants for food, medicine, and psychoactive substances.
- Hunter-gatherers possessed extensive knowledge of plants, understanding their life cycles, habitat requirements, and edible parts.
- The !Kung people of central Africa provide an example of present-day hunter-gatherers, spending about two days per week obtaining food.
Reasons for Settlement and Agriculture
- A reliable, abundant food supply was a primary incentive for settling in one place.
- Access to trade routes, year-round water supply, and favorable environments also played a role in encouraging settlement.
- Settlement led to plant cultivation and animal domestication, resulting in:
- More dependable food supplies.
- Larger human populations.
- Greater control over the environment.
- Sedentary lifestyles and permanent dwellings.
- Increased efficiency in food production, leading to more free time and specialization.
Origins of Agriculture
- Agriculture, defined as tilling land for planting crops, ensures a consistent food supply year-round.
- It arose from plant domestication and often included animal domestication.
- Archaeological evidence suggests independent development of agriculture in three regions: Asia Minor, China-Southeast Asia, and the Americas, around 5,000 to 7,000 years ago.
- The earliest evidence of agriculture comes from arid regions, particularly the Fertile Crescent in Asia Minor.
- The need for a reliable food supply in this arid region, and the presence of wild precursor crop species, are proposed reasons for its development.
- It is possible that agriculture also evolved in more humid regions, but the archaeological record is less preserved.
Domestication of Plants: Theories
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Childe's Neolithic Revolution:
- During extended dry periods, humans and animals were brought together around watering holes.
- Disturbance of the land favored the establishment of wild grasses, leading to the development of domesticated cereal crops.
- This pathway, from hunter-gatherer to animal herder and finally to plant cultivator, was proposed for the Asia Minor region.
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Sauer's Favourable Habitats:
- Human populations developed sedentary lifestyles in areas with favorable environments (mild climates, edible plants, good fishing, and water sources).
- Agricultural practices were introduced from Asia Minor into the Balkan region around 6,000 years ago.
- The cooler European climate led to a shift in crop species from wheat and barley to rye and oats.
Agriculture in Central China (Far East)
- Evidence of agriculture in central China dates back 6,000 years in the Yang-Chao site near the Yellow River.
- This region had a developed agrarian society with rice fields, villages, and social structures.
- While evidence exists in other parts of eastern Asia, preservation issues in tropical environments limit our knowledge.
- Spirit Cave in Thailand shows evidence of bean and pea cultivation 9,000 years ago and rice cultivation 7,000 years ago.
Agriculture in Central America
- The dry climate of central Mexico and Peru facilitated the preservation of archaeological material.
- Evidence of agricultural development in Central and South America dates back 7,500 years.
- At Tehuancan in Mexico, agriculture developed more slowly than at Jarmo, Iraq, a process known as incipient cultivation.
- Development occurred as follows:
- 9,000-7,000 years ago: Primarily hunter-gatherer.
- 7,000 years ago: 15% cultivation, with crops like corn, squash, peppers, amaranth, and avocado.
- 5,500 years ago: About 30% cultivation.
- 3,500 years ago: Fully agricultural, with hybrid corn, tomato, squash, bean, peppers, cotton, fruits, and domesticated dogs.
- 2,500 years ago: Irrigation and domesticated turkeys were introduced.
- Evidence also points to agricultural development in wetter regions, though material preservation is poor.
Changes in Cultivated Plants
- Loss of dependence on wild resources was a major outcome of agriculture.
- Loss of shattering: Plants were selected for seeds that stayed on the plant rather than falling off before harvest.
- Increased food reserves (starch): Plants were selected for larger seeds with more carbohydrate reserves, resulting in higher yields due to competitive advantage.
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Selection affecting weedy species:
- Weeds that germinated with crops but shed their seeds before harvest continued to reproduce.
- Some weeds mimicked crop seeds, making separation at harvest impossible.
- Rye is believed to have originated as a weed of wheat fields.
Geographic Origin and Spread of Plants
- Most of our common food plants originated in limited geographic regions.
- The introduction of new crops had significant impacts on agriculture and diets.
- Examples include the introduction of potatoes from South America to Europe, tomatoes and chili peppers from South America, and sugarcane from southeast Asia to the Caribbean.
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Europe:
- Romans introduced Mediterranean species like peas, oats, rye, and herbs into northern Europe.
- Arabs introduced rice, sugarcane, sorghum, and citrus fruits during colonization of Spain.
- European conquest of the Americas brought corn (maize) and potatoes to Europe.
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Asia:
- Asia is home to many native food plants, notably rice.
- Many cereals, cucurbits, and brassicas exhibit high mutability.
Genetic Engineering (GE)
- GE crops involve introducing genetic information from other organisms into a plant.
- GE crops like canola, soybean, and corn are engineered for pest, pathogen, and herbicide resistance.
- Concerns about GE crops include:
- Escape into natural habitats and potential harm to ecosystems.
- Safety and health concerns due to perceived unnatural nature.
- Higher cost of GE seeds, limiting access for farmers in developing nations.
Genetic Diversity
- Developing new crop varieties, crops, and medicines relies on a diverse genetic pool.
- Loss of older, less productive varieties is a concern, as they may contain valuable genes for future breeding programs.
- The loss of tropical rain forests and other ecosystems is a cause for concern as these regions are vital sources of genetic diversity.
Cereal Crops
- Cereal crops, particularly wheat, rice, and corn, are fundamental to agriculture worldwide.
- These crops are concentrated sources of carbohydrates, primarily starch, with proteins, oils, vitamins, and minerals.
- They are also suitable for long-term storage due to their low water content.
- "True" cereals are members of the Grass (Poaceae) family, a large and economically significant group of monocots.
- Grasses produce a dry, indehiscent fruit called a caryopsis, which is essentially a seed with a hard, fused pericarp (covering).
Bread Wheat (Triticum aestivum)
- Modern bread wheat originated in Asia Minor (present-day Iraq) through a series of hybridization and chromosome doubling events involving Triticum, Agropyron, and Aegilops.
- It is a hexaploid with 42 chromosomes, six times the base chromosome number (N = 7).
- Archaeological evidence suggests wheat cultivation began around 9,000 years ago in Jarmo (present-day Iraq).
- Initial processing involved heating to remove inedible parts, followed by grinding into coarse meal for porridge.
- Accidental fungal yeast infection of wheat gruel likely led to the development of leavened bread and alcoholic beverages.
- Two main types of wheat are hexaploid bread wheat (T. aestivum) and tetraploid durum wheat (T. durum).
- Durum wheat, with its hard grain and lower gluten content, is commonly used for pasta, semolina, couscous, and bulgar.
- Other wheats include diploid einkorn wheat (T. monococcum) and tetraploid emmer wheat (T. dicoccum), first cultivated in Asia Minor around 8,000 years ago.
- Spelt wheat (T. spelta), another hexaploid species, is closely related to bread wheat and grown as a specialty crop.
- Modern bread wheat varieties are categorized as spring wheat, sown in spring and harvested in autumn with a 90-day growing season, and winter wheat, sown in fall, germinates in late fall, overwinters as seedlings, and is harvested in mid-summer.
- A significant wheat pathogen is black stem rust fungus, and breeding programs focus on enhancing resistance to this and other fungal pathogens.
- A wheat grain (caryopsis) consists of three parts: the germ (embryo), rich in oils and protein, accounting for 6% of the grain; the bran (outer coating) including the seed coat, aleurone layer, and husk, rich in proteins, enzymes, and fiber, comprising about 4% of the grain; and the white flour (semolina), primarily starch, making up 85-90% of the grain, serving as the food source for the developing embryo during germination.
- Black stem fungus attacks the endosperm to utilize its energy source.
Processing of Wheat Grains
- Wheat grain processing involves cleaning, tempering, crushing, and separating.
- Cleaning removes glumes and other inedible parts.
- Tempering involves moistening the grain to toughen the bran and prevent fragmentation.
- Crushing separates the bran and germ (high in proteins, minerals, fats, and vitamins), used for cattle feed, breakfast cereals, and whole-grain flours.
- Separating focuses on the endosperm (white flour or semolina), primarily high-energy starch.
- White flour, lacking bran and germ, has a longer shelf life but lacks essential proteins and vitamins.
- Enrichment processes add vitamins to white flour.
- Wheat is unique among cereal grains in containing all the gluten proteins necessary for traditional bread-making.
- During baking, yeast ferments sugars in flour dough, releasing carbon dioxide (CO2) which gets trapped by gluten, creating bubbles and causing the dough to rise, resulting in leavened bread.
Corn or Maize (Zea mays)
- Corn, native to Central America, has been cultivated for at least 7,000 years.
- Early cultivars and genetic crosses were selected during crop domestication in Mexico and Peru.
- It played a critical role in the development of the Mayan, Aztec, and Inca civilizations.
- Modern corn is a mutation of ancestral plant teosinte.
- Corn has separate male (tassels) and female (ears) flowers.
- Corn is low in protein, especially lysine, and some vitamins like niacin compared to other cereals.
- Its lack of gluten proteins limits its flour use primarily to flatbreads like tortillas.
- Despite its subtropical origins, modern varieties grow well in temperate climates.
- It has a short growing season.
- Primarily used for livestock feed, human consumption, and bioethanol production.
- Sweet corn is consumed fresh, canned, or frozen, and processed into flour and meal.
- Livestock feed varieties are starchy, not sweet.
- Other cultivars include popping corn, beer, cornstarch, and specialty products.
- Corn is genetically mutable and hybridizes easily, crucial for crop production.
Rice (Oryza sativa)
- Rice processing involves threshing to separate grains from chaff and pearling/polishing to produce white rice, removing the bran and germ.
- Polished white rice grains are about 92% starch and have low protein content.
- They contain hard starch and lack gluten proteins.
- Polishing removes thiamine (vitamin B1), potentially leading to thiamine deficiency and beriberi.
- Symptoms of beriberi include weight loss, reduced sensory perception, limb pain and weakness, and emotional disturbances.
Some Other Cereal Crops
Oats (Avena sativa)
- Oats are an important forage and fodder for cattle.
- About 4% is consumed by humans, primarily as oatmeal and rolled oats.
- Oats have the highest protein content among cereals but lack gluten proteins.
- Cultivated in moist-temperate areas, with both spring and winter varieties.
Rye (Secale cereale)
- Rye likely originated as a cultivar of S. montanum, a weed mimicking wheat and barley crops.
- It thrives in cool climates and tolerates nutrient-poor soils.
- Primarily grown as fodder, but also used for bread flour, especially in Eastern Europe and Russia.
- Low gluten content results in dense, dark, and bitter bread.
- North American rye breads often contain 50-90% wheat flour.
- Rye can be infected with fungal ergot, causing symptoms like convulsions, paralysis, gangrene, and hallucinations in humans.
- Ergot contains Ergotamine, LSD, and alkaloid compounds with dangerous physiological effects.
- Historically, ergot poisoning led to events like witch trials, demonic possessions, and religious visions.
- Large-scale epidemics persisted into the 20th century, with the last reported case in 1951 in France.
- Monitoring and careful management have reduced outbreaks in developed countries.
Sorghum (Sorghum bicolor)
- Sorghum, an annual grass native to Africa, is cultivated in Asia, India, Africa, and the southern United States.
- Thrives in warm to hot temperatures and is drought-resistant.
- Traditionally used as unleavened bread in Africa but largely replaced by wheat.
- In the U.S., primarily used as forage for cattle and pigs.
- The flowering head can be dried to make brooms.
- High in carbohydrates (60-75%) and protein (8-13%).
Barley (Hordeum vulgare)
- Early evidence of barley cultivation from both Asia Minor and Northeast Africa suggests it may be the first domesticated cereal.
- Both two-row and six-row varieties exist.
- Primarily grown in cool-temperate climates, with spring and winter varieties.
- Tolerates salinity and can be grown on marginal soils.
- Approximately 70% is used as animal fodder.
- The remaining 30% is used for malt barley, processed through soaking, germination, and drying to concentrate germinated material into thick syrupy malt.
- Malt barley is a primary ingredient in commercial beers and whiskeys.
Millets (Various Species)
- "Millet" refers to several cereal crop species grown in hot, dry tropical regions, widely cultivated in India, Pakistan, and parts of Africa.
- Tolerate drought and poor soil conditions.
- Whole grains store well but quickly turn rancid when ground.
- Lacking gluten proteins, they cannot be used for leavened bread.
Fruit Definition
- A fruit is a mature, ripened ovary of a flowering plant that contains seeds.
- The ovary wall becomes the pericarp (exocarp, mesocarp, and endocarp), which encloses the seeds.
- Superior ovary is on top of the flower.
- Inferior ovary is below the flower.
- Fleshy fruits are juicy and watery (apple, oranges).
- Dry fruits are not watery (nuts, grains).
- Simple fruit develops from one ovary on one flower.
- Aggregate fruit develops from the fusion of multiple ovaries on one flower.
- Multiple fruit develops from multiple ovaries and multiple flowers.
Rose Family (Rosaceae)
- Large family of eudicots, primarily temperate species.
- Showy flowers are pollinated by insects.
- Fruits are fleshy, large, and dispersed by animals.
- Economically important for food production.
- Consists of four subfamilies: Rosoideae, Prunoideae, Maloideae, and Spiraeoideae.
Subfamily Rosoideae
- Includes raspberry (Rubus idaeus), blackberry (R. fruticosus), and strawberry (Fragaria ananassa).
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Aggregate fruits are not true berries, and two types are distinguished:
- Rubus genus (raspberry and blackberry): Receptacle remains when picked, creating a hollow appearance. Consists of loosely attached drupelets.
- Fragaria genus (strawberry): Receptacle becomes fleshy and sweet, with nutlets (seeds) attached.
- Drupelets are small fruits with a single seed encased in sweet pulp.
Subfamily Prunoideae
- Includes plum (Prunus domestica), peach and nectarine (P. persica), apricot (P. armeniaca), cherry (P. avium), and almond (P. dulcis).
- Mostly native to Eastern and Central Asia.
- Drupes develop from a single ovule, resulting in one seed per fruit.
- Exocarp & mesocarp are eaten, while the endocarp (stone) is discarded.
- Almond is a roasted seed, with a bitter, inedible pericarp.
Subfamily Maloideae
- Includes apple (Malus domestica), pear (Pyrus communis), and quince (Cydonia oblonga).
- Pomes develop from an inferior ovary, with the sweet portion derived from hypanthium tissue.
- The inedible pericarp is the core containing seeds.
- Most apple and pear varieties originated in Eastern and Central Asia.
- Apple varieties are derived from Malus domestica.
- Older varieties are diploid and produce viable seeds, while modern cultivars are triploid and sterile.
Tomato Family (Solanaceae)
- Large eudicot family with worldwide distribution.
- Important for agricultural development in South and Central America.
- Includes domesticated species like tobacco, potato, and medicinal/poisonous plants.
- True berries in botanical terms.
Tomato (Lycopersicon esculentum)
- Native to Central America, first domesticated by the Mayans.
- Initially not accepted in Europe due to poisonous relatives (henbane, deadly nightshade, belladonna).
- Wild progenitor was smaller and more pungent than modern cultivars.
Sweet and Capsicum Peppers
- Capsicum annuum and C. frutescens originated in Central America.
- Widely hybridized within the genus Capsicum, with varying sizes and "hotness" levels.
- Hotness due to capsaicin concentrated in the fruit's placental tissue.
- Used in various cuisines globally.
- Possibly used to mask the smell of unrefrigerated food.
Mulberry Family (Moraceae)
- Economically important members produce multiple fruits.
- White and black mulberries (Morus alba and M. nigra) are minor temperate crops.
- Figs (Ficus carica) are commercially significant subtropical fruits.
- Breadfruit and jackfruit are important carbohydrate sources in the tropics.
Other Temperate Fruits
- Grape (Vitis vinifera) is a large perennial woody vine native to the Eastern Mediterranean.
- Used for fresh consumption, dried into raisins, and wine production.
- Pomegranate (Punica grantum) is a small tree native to the Middle East.
- Multi-seeded fruit with aril pulp, used for juice production.
- Kiwi (Actinidia deliciosa) is indigenous to China, commercialized in New Zealand.
- Olive (Olea europea) is a large, long-lived tree native to the Mediterranean.
- Fruit used for cooking oil and processed as food (needs treatment with caustic soda).
Other Tropical Fruits
- Many subtropical and tropical fruits are wild-harvested or grown commercially.
- Some are available in North America, while others are consumed locally.
- Coconut is highly versatile, providing food, clothing, building materials, and drinking vessels.
Commercially Important Dicots
- Durian (Durio zibethinus) is a tall tree native to western Malaysia.
- Large, prickly fruit with fleshy pulp surrounding seeds.
- Known for its pungent aroma, complex flavor, and creamy texture.
- Avocado (Persea americana) is a large tree indigenous to Central America.
- Fruit rich in oil (uncommon in flowering plants).
- High in calories and vitamins A, C, niacin, and riboflavin.
- Mango (Mangifera indica) is a large tree native to India and Malaysia.
- Cultivated for at least 4,000 years.
- Fruit is available globally, with both ripe (sweet dessert) and unripe (sour, used in cooking) varieties.
- Papaya (Carica papaya) is a small tree indigenous to Central America.
- Large, yellow fruit popular in tropical countries, now available globally.
Nuts
- Botanically, nuts are dry, one-seeded fruits with a hard, woody pericarp.
- Common definition refers to edible, high-protein seeds from specific plant species.
Walnut (Juglans regia)
- Large tree indigenous to Southeast Europe and Western Asia.
- Bitter-tasting, drupe-like fruit.
- Processed to remove the exocarp and mesocarp, leaving the woody endocarp (shell) containing the edible seed.
- Seeds can be processed into cooking oil.
Legumes
- Also known as pulses, are members of the Fabaceae (Legume or Pea) family.
- Fabaceae family includes both herbaceous plants (e.g., peas, beans, lupines) and woody trees (e.g., acacia, tamarind, and many tropical rainforest trees).
- Legumes are single-chambered pods with seeds attached along one edge.
- Legume seeds are high in protein, up to 25-30%, comparable to red meat.
- They are a crucial protein source, especially in areas where meat is unavailable or expensive.
- Legumes contain all essential amino acids making them vital for vegetarians and those opposed to eating meat.
- Legumes are high-protein forage for domestic animals, like clover, sweet-clover, and alfalfa.
- Legumes produce root nodules containing nitrogen-fixing bacteria (Rhizobium), which convert atmospheric nitrogen (N
2) into nitrate (NO3) usable by plants. - This mutualistic relationship benefits both the legumes and bacteria with the plants providing sugars from photosynthesis and receiving essential nitrogen in return.
Economically Important Legumes
Common or Kidney Bean
- Native to Central and South America.
- Cultivars include fresh pods (green or string beans), or dried seeds (kidney beans).
- Dried kidney beans contain ~20% protein.
Pea
- Ancient legume crop, cultivated for at least 7,000 years.
- Believed to be native to the Mediterranean, Middle East (Southwest Asia), and northeastern Africa.
- Seeds may be dried (~25% protein) or eaten fresh.
- Sugar peas have pods that are eaten fresh.
- Important source of protein in Medieval Europe.
Soybean
- Native to China, Japan, and Korea (East Asia).
- Cultivated over 3,000 years ago in northeast China.
- Seeds contain high levels of protein (35-40% dry weight) and all essential amino acids.
- Economically, it’s the world's most important legume crop, producing over 100 million tons annually.
- Largest producers include the United States, China, and Brazil.
- Soybeans need warm temperatures and a long growing season.
- Versatile uses including fresh and dried beans, bean sprouts, edible oils, industrial oils, Asian food products (e.g., miso, tofu, soy sauce, soy flour), processed protein products, food additives, and livestock and pet food.
Peanut or Groundnut
- Native to Central and South America, domesticated over 3,500 years ago.
- Though often classified as a "nut," it's a legume.
- Two main types: prostrate Virginia and upright Spanish.
- Over 30 million tons harvested annually, with India, China, Nigeria, and the United States being the major producers.
- Unique features include flower stalks elongating after pollination, pushing the maturing fruit into the soil.
- Best grown in loose, sandy soils.
- Processed into edible and industrial oils or used for animal feed.
- Typically roasted if eaten as a snack and processed into pastes (peanut butter) and sauces (satay).
- Added directly into stews and stir-fries.
Tropical Pulses
- Provide a significant seed protein source in India, Africa, Asia, and South America.
Lima Bean
- Big green beans native to Central and South America.
Broad Bean
- Originated in the old world and has been grown for centuries.
Chickpea
- One of the oldest cultivated legumes.
- Used for hummus and key in Mediterranean and Middle Eastern cuisine.
Black Gram or Urd
- Black beans with a white line.
Mung Bean or Green Gram
- Like black gram but green instead with a white line.
Black-eyed Bean
- White with black stripes.
Asparagus or Yard-long Bean
- Viny, can climb up to 12ft
Pigeon Pea
- Hardy and can grow in poor soil conditions.
Lentil
- Ancient crop from Southwest Asia.
- Widely grown on the Indian subcontinent to produce dahl, a lentil puree.
- Drought-tolerant species with numerous cultivars.
Other Legumes
Carob
- Subtropical tree native to the Arabian Peninsula (Southwest Asia).
- Pods known as St.John's Bread, contain protein and sugar rich seeds.
- Pods sold fresh for the edible "sweetmeat."
- Processed into a paste used as a chocolate substitute.
- Seeds used for stabilizing agents in food products (e.g., ice cream, salad dressing, processed meats).
Tamarind
- Large tree native to India.
- Like carob, it has large pods.
- Sweet meat around the seeds is used.
- Important in Indian, Filipino, Middle Eastern cuisines.
Fenugreek
- Native to the Mediterranean and Southwest Asia.
- Seeds used medicinally and as a food source since ancient times.
- Important crop in India, the Middle East, and Africa.
- Fenugreek seed is an important spice.
- Fresh leaves used in India as a vegetable.
- Dried leaves used as an aromatic spice.
Liquorice
- Native to the Mediterranean region and central Asia.
- Known to the ancient Greeks and Romans.
- Cultivated for centuries as a flavoring and sweetener.
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