The Three Sisters are the three main agricultural crops of various

Indigenous peoples of North America The Indigenous peoples of the Americas are the inhabitants of the Americas before the arrival of the European settlers in the 15th century, and the ethnic groups who now identify themselves with those peoples. Many Indigenous peoples of the Am ...

squash Squash may refer to: Sports * Squash (sport), the high-speed racquet sport also known as squash racquets * Squash (professional wrestling), an extremely one-sided match in professional wrestling * Squash tennis, a game similar to squash but pla ...

maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...

("corn"), and climbing

bean A bean is the seed of several plants in the family Fabaceae, which are used as vegetables for human or animal food. They can be cooked in many different ways, including boiling, frying, and baking, and are used in many traditional dishes th ...

s (typically

tepary bean ''Phaseolus acutifolius'', also known as the tepary bean, is a legume native to the southwestern United States and Mexico and has been grown there by the native peoples since pre-Columbian times. It is more drought-resistant than the common bean ...

s or

common bean ''Phaseolus vulgaris'', the common bean, is a herbaceous annual plant grown worldwide for its edible dry seeds or green bean, green, unripe pods. Its leaf is also occasionally used as a Leaf vegetable, vegetable and the straw as fodder. Its Pla ...

s). In a technique known as

companion planting Companion planting in gardening and agriculture is the planting of different crops in proximity for any of a number of different reasons, including pest control, pollination, providing habitat for beneficial insects, maximizing use of space, and ...

, the maize and beans are often planted together in mounds formed by

hilling Hilling, earthing up or ridging is the technique in agriculture and horticulture of piling soil up around the base of a plant. It can be done by hand (usually using a hoe), or with powered machinery, typically a tractor attachment. Hilling burie ...

soil around the base of the plants each year; squash is typically planted between the mounds. The cornstalk serves as a trellis for climbing beans, the beans fix nitrogen in their

root nodule Root nodules are found on the roots of plants, primarily legumes, that form a symbiosis with nitrogen-fixing bacteria. Under nitrogen-limiting conditions, capable plants form a symbiotic relationship with a host-specific strain of bacteria known a ...

s and stabilize the maize in high winds, and the wide leaves of the squash plant shade the ground, keeping the soil moist and helping prevent the establishment of

weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...

s. Indigenous peoples throughout North America cultivated different varieties of the Three Sisters, adapted to varying local environments. The individual crops originated in

Mesoamerica Mesoamerica is a historical region and cultural area in southern North America and most of Central America. It extends from approximately central Mexico through Belize, Guatemala, El Salvador, Honduras, Nicaragua, and northern Costa Rica. W ...

; squash was domesticated first, followed by maize and then beans, over a period of 5,000–6,500 years. European records from the sixteenth century describe highly productive Indigenous agriculture based on cultivation of the Three Sisters throughout what are now the Eastern United States and Canada, where the crops were used for both food and trade. Geographer

Carl O. Sauer Carl Ortwin Sauer (December 24, 1889 – July 18, 1975) was an American geographer. Sauer was a professor of geography at the University of California at Berkeley from 1923 until becoming professor emeritus in 1957. He has been called "the d ...

described the Three Sisters as "a symbiotic plant complex of North and Central America without an equal elsewhere".

Cultivation methods

In indigenous American

, maize (''

Zea mays Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...

''), beans ('' Phaseolus'' and ''

Vicia ''Vicia'' is a genus of over 240 species of flowering plants that are part of the legume family (Fabaceae), and which are commonly known as vetches. Member species are native to Europe, North America, South America, Asia and Africa. Some other ...

'' spp.), and squash (''

Cucurbita pepo ''Cucurbita pepo'' is a cultivated plant of the genus ''Cucurbita''. It yields varieties of winter squash and pumpkin, but the most widespread varieties belong to the subspecies ''Cucurbita pepo'' subsp. ''pepo'', called summer squash. It has b ...

'') are planted close together. The maize and beans are often planted together in mounds formed by

soil around the base of the plants each year; squash is typically planted between the mounds. In the northeastern U.S., this practice increases soil temperature in the mound and improves

drainage Drainage is the natural or artificial removal of a surface's water and sub-surface water from an area with excess of water. The internal drainage of most agricultural soils is good enough to prevent severe waterlogging (anaerobic conditio ...

, both of which benefit maize planted in spring. Each mound is about high and wide, and several maize seeds are planted close together in the center of each mound; in parts of the

Atlantic Northeast , settlement_type = Region , image_skyline = , imagesize = , image_alt = , image_caption = , image_flag = , flag_alt = , image_seal = , seal_ ...

, rotten fish or eels are buried in the mound with the maize seeds, to act as additional fertilizer where the soil is poor. In

Haudenosaunee The Iroquois ( or ), officially the Haudenosaunee ( meaning "people of the longhouse"), are an Iroquoian Peoples, Iroquoian-speaking Confederation#Indigenous confederations in North America, confederacy of First Nations in Canada, First Natio ...

(Iroquois) farming, the fields were not

tilled Tillage is the agricultural preparation of soil by mechanical agitation of various types, such as digging, stirring, and overturning. Examples of human-powered tilling methods using hand tools include shoveling, picking, mattock work, hoein ...

, enhancing soil fertility and the sustainability of the cropping system by limiting soil erosion and oxidation of

soil organic matter Soil organic matter (SOM) is the organic matter component of soil, consisting of plant and animal detritus at various stages of decomposition, cells and tissues of soil microbes, and substances that soil microbes synthesize. SOM provides numerous b ...

. The three crops benefit by being grown together. The cornstalk serves as a trellis for the beans to climb, the beans fix nitrogen in the soil, and their twining vines stabilize the maize in high winds, and the wide leaves of the squash plant shade the ground, keeping the soil moist and helping prevent the establishment of

s. The prickly hairs of some squash varieties also deter pests, such as

deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...

and

raccoon The raccoon ( or , ''Procyon lotor''), sometimes called the common raccoon to distinguish it from other species, is a mammal native to North America. It is the largest of the procyonid family, having a body length of , and a body weight of ...

s. Although this synergy had been traditionally reputed among American cultures, scientific confirmation has arrived only much more recently. Much of this research was performed in the Soviet Union in the early 1970s and published in several volumes of ''Biochemical and Physiological Bases for Plant Interactions in Phytocenosis'' edited by . Dzubenko & Petrenko 1971, Lykhvar & Nazarova 1970 and Pronin ''et al.'' 1970 find a wide number of leguminous crops increase the growth and yield of maize, while Gulyaev ''et al.'' 1970 select later maturing lines of beans to produce the converse effect, increasing even further the yield gain of beans when planted with maize. Pronin ''et al.'' 1972 find increased productivity and

root exudate Plant root exudates are fluids emitted through the roots of plants. These secretions influence the rhizosphere around the roots to inhibit harmful microbes and promote the grow of self and kin plants. Plant root systems can grow to be complex due t ...

in both crops when combining ''

Vicia faba ''Vicia faba'', commonly known as the broad bean, fava bean, or faba bean, is a species of vetch, a flowering plant in the pea and bean family Fabaceae. It is widely cultivated as a crop for human consumption, and also as a cover crop. Varieti ...

'' with maize, and even more so in soils with preexisting high nitrogen fixing microorganism activity. Three Sisters mound culture in Arizona Mountains

Three Sisters mound culture in Arizona Mountains

Indigenous peoples throughout North America cultivated different varieties of the Three Sisters, adapted to varying local environments. The ''

milpa Milpa is a crop-growing system used throughout Mesoamerica. It has been most extensively described in the Yucatán peninsula area of Mexico. The word ''milpa'' is derived from the Nahuatl word phrase ''mil-pa'', which translates into "cultivated ...

s'' of

are farms or gardens that employ companion planting on a larger scale. The

Ancestral Puebloans The Ancestral Puebloans, also known as the Anasazi, were an ancient Native American culture that spanned the present-day Four Corners region of the United States, comprising southeastern Utah, northeastern Arizona, northwestern New Mexico, a ...

adopted this garden design in the drier

deserts and xeric shrublands Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (ancient Greek xērós, “dry") shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this ...

environment. The

Tewa The Tewa are a linguistic group of Pueblo Native Americans who speak the Tewa language and share the Pueblo culture. Their homelands are on or near the Rio Grande in New Mexico north of Santa Fe. They comprise the following communities: * ...

and other peoples of the North American Southwest often included a "fourth Sister", Rocky Mountain bee plant ('' Cleome serrulata''), which attracts bees to help pollinate the beans and squash. The Three Sisters crop model was widely used by a number of

First Nations First Nations or first peoples may refer to: * Indigenous peoples, for ethnic groups who are the earliest known inhabitants of an area. Indigenous groups *First Nations is commonly used to describe some Indigenous groups including: **First Natio ...

in the

Great Lakes–St. Lawrence Lowlands The Great Lakes-St. Lawrence Lowlands, or simply St. Lawrence Lowlands, is a physiographic region of Eastern Canada that comprises a section of southern Ontario bounded on the north by the Canadian Shield and by 3 of the Great Lakes — Lake Huron ...

region.

Productivity

European records from the sixteenth century describe highly productive Indigenous agriculture based on cultivation of the Three Sisters throughout what are now the

Eastern United States The Eastern United States, commonly referred to as the American East, Eastern America, or simply the East, is the region of the United States to the east of the Mississippi River. In some cases the term may refer to a smaller area or the East C ...

and Canada, from Florida to Ontario. Geographer

described the Three Sisters as "a symbiotic plant complex of North and Central America without an equal elsewhere". Agronomist Jane Mt. Pleasant writes that the Three Sisters mound system "enhances the soil physical and biochemical environment, minimizes soil erosion, improves soil

tilth Tilth is a physical condition of soil, especially in relation to its suitability for planting or growing a crop. Factors that determine tilth include the formation and stability of aggregated soil particles, moisture content, degree of aeration, ...

, manages plant population and spacing, provides for plant nutrients in appropriate quantities, and at the time needed, and controls weeds". Nutritionally, maize, beans, and squash contain all nine

essential amino acids An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life form ...

, as well as complex

carbohydrates In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or may ...

and essential

fatty acids In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, f ...

. The

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

from maize is further enhanced by protein contributions from beans and

pumpkin A pumpkin is a vernacular term for mature winter squash of species and varieties in the genus ''Cucurbita'' that has culinary and cultural significance but no agreed upon botanical or scientific meaning. The term ''pumpkin'' is sometimes use ...

seeds, while pumpkin flesh provides large amounts of

vitamin A Vitamin A is a fat-soluble vitamin and an essential nutrient for humans. It is a group of organic compounds that includes retinol, retinal (also known as retinaldehyde), retinoic acid, and several provitamin A carotenoids (most notably bet ...

; with the Three Sisters, farmers harvest about the same amount of energy as from maize

monoculture In agriculture, monoculture is the practice of growing one crop species in a field at a time. Monoculture is widely used in intensive farming and in organic farming: both a 1,000-hectare/acre cornfield and a 10-ha/acre field of organic kale are ...

, but get more protein yield from the inter-planted bean and pumpkin. Mt. Pleasant writes that this largely explains the value of the Three Sisters over monoculture cropping, as the system yields large amounts of energy, and at the same time increases protein yields; this

polyculture In agriculture, polyculture is the practice of growing more than one crop species in the same space, at the same time. In doing this, polyculture attempts to mimic the diversity of natural ecosystems. Polyculture is the opposite of monoculture, i ...

cropping system yielded more food and supported more people per hectare compared to monocultures of the individual crops or mixtures of monocultures.

Society and culture

Maize, beans, and squash, whether grown individually or together, have a very long history in the Americas. The process to develop this agricultural knowledge took place over 5,000–6,500 years. Squash was domesticated first, with maize second and beans third. Squash was first domesticated 8,000–10,000 years ago.

Cahokian, Mississippian and Muscogee culture

Corn, squash and beans were planted ca. 800 AD in the largest Native American city north of the

Rio Grande The Rio Grande ( and ), known in Mexico as the Río Bravo del Norte or simply the Río Bravo, is one of the principal rivers (along with the Colorado River) in the southwestern United States and in northern Mexico. The length of the Rio G ...

known as

Cahokia The Cahokia Mounds State Historic Site ( 11 MS 2) is the site of a pre-Columbian Native American city (which existed 1050–1350 CE) directly across the Mississippi River from modern St. Louis, Missouri. This historic park lies in south- ...

, in the present US state of

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

, across the Mississippi River from

St. Louis, Missouri St. Louis () is the second-largest city in Missouri, United States. It sits near the confluence of the Mississippi River, Mississippi and the Missouri Rivers. In 2020, the city proper had a population of 301,578, while the Greater St. Louis, ...

. The Three Sisters crops were responsible for the surplus food that created an expanded population throughout the extended

Mississippi River System The Mississippi River System, also referred to as the Western Rivers, is a mostly riverine network of the United States which includes the Mississippi River and connecting waterways. The Mississippi River is the largest drainage basin in the Unit ...

, creating the Mississippian and

Muscogee The Muscogee, also known as the Mvskoke, Muscogee Creek, and the Muscogee Creek Confederacy ( in the Muscogee language), are a group of related indigenous (Native American) peoples of the Southeastern Woodlands In the ''

Handbook of North American Indians The ''Handbook of North American Indians'' is a series of edited scholarly and reference volumes in Native American studies, published by the Smithsonian Institution beginning in 1978. Planning for the handbook series began in the late 1960s and ...

'', the Three Sisters are called the "foundation of (Iroquois) subsistence", allowing the

or Iroquois to "develop the institutions of sedentary life". The Three Sisters appear prominently in Haudenosaunee oral traditions and ceremonies, such as the

creation story A creation myth (or cosmogonic myth) is a symbolic narrative of how the world began and how people first came to inhabit it., "Creation myths are symbolic stories describing how the universe and its inhabitants came to be. Creation myths develop ...

and the thanksgiving address. Researchers in the early 20th century described more than a dozen varieties of maize and similar numbers of bean varieties, as well as many types of squash, such as pumpkin and

winter squash Winter squash is an annual fruit representing several squash species within the genus ''Cucurbita''. Late-growing, less symmetrical, odd-shaped, rough or warty varieties, small to medium in size, but with long-keeping qualities and hard rinds, are ...

, grown in Haudenosaunee communities. The first academic description of the Three Sisters cropping system in 1910 reported that the Iroquois preferred to plant the three crops together, since it took less time and effort than planting them individually, and because they believed the plants were "guarded by three inseparable spirits and would not thrive apart". Among the Haudenosaunee, women were responsible for cultivation and distribution of the three crops, which raised their social status. Male roles traditionally included extended periods of travel, such as for hunting expeditions, diplomatic missions, or military raids. Men took part in the initial preparation for the planting of the Three Sisters by clearing the planting ground, after which groups of related women, working communally, performed the planting, weeding, and harvesting. Based on archaeological findings, paleobotanist John Hart concludes that the Haudenosaunee began growing the three crops as a polyculture sometime after 700 BP. The Haudenosaunee frequently traded their crops, so the need for each crop could vary substantially from year to year. Jane Mt. Pleasant surmises that the Haudenosaunee may have typically inter-planted the three crops, but they could also have planted monocultures of the individual crops to meet specific needs.

Maya culture

The Maya diet focused on three domesticated staple crops: maize,

, and

s (typically ''

Phaseolus vulgaris ''Phaseolus vulgaris'', the common bean, is a herbaceous annual plant grown worldwide for its edible dry seeds or green, unripe pods. Its leaf is also occasionally used as a vegetable and the straw as fodder. Its botanical classification, alo ...

''). Among the three, maize was the central component of the diet of the ancient Maya and figured prominently in

Maya mythology Maya or Mayan mythology is part of Mesoamerican mythology and comprises all of the Maya tales in which personified forces of nature, deities, and the heroes interacting with these play the main roles. The myths of the era have to be reconstruct ...

and

ideology An ideology is a set of beliefs or philosophies attributed to a person or group of persons, especially those held for reasons that are not purely epistemic, in which "practical elements are as prominent as theoretical ones." Formerly applied pri ...

. Archaeological evidence suggests that Chapalote-Nal-Tel was the dominant maize species, though it is likely others were being exploited also. Maize was used and eaten in a variety of ways, but was always

nixtamalized Nixtamalization () is a process for the preparation of corn, or other grain, in which the grain is soaked and cooked in an alkaline solution, usually limewater (but sometimes aqueous alkali metal carbonates), washed, and then hulled. The term ...

Cultivation methods

Productivity

Society and culture

Cahokian, Mississippian and Muscogee culture

Maya culture

See also

References

Further reading