Amaranth (Amaranthus): The Aztec Grain Cortés Banned Under Penalty of Death in 1521

What is Amaranth?

On August 13, 1521, the city of Tenochtitlan fell to the Spanish. Within weeks, Hernán Cortés issued a decree that would shape the food history of two continents. Cultivation of the grain the Aztecs called huauhtli was forbidden under penalty of death. Possession of its tiny seeds was a capital offense. Any farmer caught growing it would have his hands cut off. Cortés is documented as saying he would carry out the punishment personally. Across the empire, fields were torched, stored grain was burned, and seed stocks were destroyed with the same systematic brutality the conquistadors applied to Aztec temples.

For roughly 400 years, the grain virtually disappeared from cultivation. It survived only in remote mountain villages where Indigenous families hid seeds in clay vessels buried underground, planted small plots away from Spanish eyes, and passed cultivation knowledge to their children in whispers. Growing this grain became an act of cultural resistance. Saving its seeds became an act of survival.

This is amaranth, genus Amaranthus, a pseudo-cereal in the family Amaranthaceae. The cultivated grain species are Amaranthus cruentus, A. hypochondriacus, and the Andean A. caudatus. The plant grows 4 to 8 feet tall, produces tall plumes of crimson, gold, or green flowers, and yields between 50,000 and 100,000 seeds per plant in a season. The seeds are smaller than poppy seeds. The leaves are edible like spinach. The grain contains 14 to 19 percent protein by weight, higher than wheat or rice, and is the only common cereal that contains all nine essential amino acids in significant concentrations. Its lysine content of 5.3 to 6.3 percent is twice the lysine of wheat and three times the lysine of corn. The World Health Organization rates its amino-acid profile as nutritionally equivalent to animal protein. NASA selected it for spaceflight in the 1980s. Its wild cousin, Amaranthus palmeri, is now the most herbicide-resistant weed in American agriculture, the trigger for tens of billions of dollars in annual herbicide spending. The grain conquistadors banned for being too sacred is the same plant industrial agriculture now fights for being too uncontrollable.

Tenochtitlan, the Florentine Codex & the 1521 Ban

The archive opens in 1325. The Mexica people, who would become known as the Aztecs, are building a city on an island in the middle of Lake Texcoco. They call it Tenochtitlan. Within two centuries it will hold around 300,000 inhabitants, larger than any contemporary European city. Feeding that many people on an island required agricultural genius. The Aztecs answered with chinampas: floating gardens woven from reeds, packed with lake sediment, anchored to the lakebed by willows, and irrigated by capillary action through their own walls. On these artificial islands they grew the trinity that sustained the empire: corn, beans, and huauhtli.

Huauhtli: A Foundation, Not a Side Crop

The Matrícula de Tributos, the Aztec tax codex compiled before the conquest, lists huauhtli alongside corn, beans, cacao, and gold as essential tribute. Under Montezuma II, around 20,000 tons of amaranth grain flowed into Tenochtitlan every year from 20 tribute provinces, with roughly 5,000 hectares dedicated to its cultivation. The Florentine Codex, compiled by the Spanish friar Bernardino de Sahagún in the 1500s with Indigenous informants and illustrators, contains detailed images of Aztec farmers harvesting amaranth, threshing the seed, and storing it in clay vessels. The grain appears in tamales mixed with corn, in everyday porridge, and popped like miniature popcorn and bound with honey or agave, the original form of the modern Mexican sweet alegría.

The Communion of Huitzilopochtli

Amaranth's role went beyond calories. During festivals of Huitzilopochtli, the Aztec god of sun and war, priests mixed amaranth seed with blood drawn from sacrificial offerings and shaped the paste into statues of the deity. The figures were worshipped, then broken into pieces and distributed to the people for eating. A communion. A sacred act. A way to literally consume divinity. To the Catholic Church arriving with the conquistadors, this was unforgivable. It looked like an inversion of the Eucharist, the body and blood of Christ, performed by people the Spanish had already declared demonic. Amaranth was no longer just a food; it had become a theological enemy.

August 13, 1521: The Ban Under Penalty of Death

Tenochtitlan fell on August 13, 1521. Cortés issued the decree. Cultivation of amaranth was forbidden. Possession of seed was punishable by death. Any farmer caught growing it would have his hands severed. Historical accounts document Cortés saying he would carry out the punishment personally. Spanish forces moved village to village burning fields, destroying stored grain, and confiscating seed stocks. The ban held for roughly 400 years.

Survival in the Mountains: The 400-Year Hiding

Amaranth survived because Indigenous farmers refused to let it die. In remote highland villages of Mexico, Guatemala, and the Peruvian Andes, families hid seeds in buried clay vessels, planted small plots away from Spanish observers, and taught children the cultivation in private. By the time researchers in the 1970s went looking for the lost grain, they did not find it in gene banks or research stations. They found it in the hands of farming communities who had been growing it continuously for centuries while the rest of the world forgot it existed. The seeds that NASA would later select for spaceflight came from those families. That is not a footnote. That is the entire story.

Modern Science: Lysine, Squalene & the NASA Selection

Modern nutritional analysis has confirmed, in laboratory terms, what Aztec mothers knew when they weaned children on amaranth porridge. The grain is a near-complete human food.

14 to 19 Percent Protein With All Nine Essential Amino Acids

Most plant proteins are incomplete. Wheat is deficient in lysine. Corn is deficient in lysine and tryptophan. Rice is deficient in lysine. To build complete protein from grains, traditional cuisines pair them with legumes: rice and beans, corn and beans, wheat and lentils. Amaranth removes the requirement. It contains all nine essential amino acids the human body cannot synthesize on its own: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. The World Health Organization compared amaranth's amino-acid profile to its recommended standard for human nutrition and rated it as nutritionally equivalent to animal protein. The Food and Agriculture Organization reports protein digestibility approaching 90 percent: the body absorbs and uses almost all of what it consumes.

The Lysine Advantage

Lysine is the limiting amino acid in nearly every cereal grain: the one in shortest supply, and therefore the one that caps how much of the rest your body can use. Wheat contains 2 to 3 percent lysine. Corn contains less. Amaranth contains 5.3 to 6.3 percent lysine, roughly twice the wheat figure and three times the corn figure. Lysine is essential for calcium absorption, collagen synthesis, antibody formation, and growth-hormone regulation. A diet adequate in calories but deficient in lysine produces malnutrition even on a full stomach, the silent form of hunger that has shaped public-health outcomes across cereal-dependent populations for centuries. Amaranth eliminates that deficiency from a single grain.

Squalene, Iron and the Antioxidant Profile

Beyond protein, amaranth is unusually rich in iron, calcium, magnesium, and phosphorus, and contains a measurable concentration of squalene, an antioxidant terpene otherwise found mainly in shark liver oil. Squalene protects cells from free-radical damage and is used in cosmetic and pharmaceutical formulations harvested industrially from sharks. Amaranth produces it from a seed. The grain is naturally gluten-free, which matters both for the rising population of celiac and gluten-sensitive eaters and for any food-security context where wheat is unavailable.

1980s: The NASA Selection

In the 1980s, NASA evaluated crops for closed life-support systems on long-duration missions and selected amaranth for shuttle flights. Three properties drove the decision. First, the nutritional density: complete protein with high lysine for astronauts losing bone density and muscle mass in microgravity, plus iron, calcium, and the squalene antioxidant profile. Second, the gluten-free composition for crew members with sensitivities. Third, atmospheric regulation: amaranth uses C4 photosynthesis and converts carbon dioxide into oxygen with exceptional efficiency, so the same plants that produce edible leaves and seeds also scrub CO₂ from the recycled cabin air. The grain that fed Tenochtitlan in 1500 was, by 1985, riding the Space Shuttle.

Why It Stays Buried: Palmer Amaranth and the $40 Billion Herbicide War

The 1521 ban is the historical reason amaranth disappeared. The reason it is still not a staple in supermarkets, school lunches, or food-aid programs is more recent and more economic. It comes down to a single feature the plant could not be designed out of: it does not need help.

The Superweed: Amaranthus palmeri

Palmer amaranth (Amaranthus palmeri) is the wild cousin of the cultivated grain. Same genus. Same family. Different breeding history. Where Indigenous farmers selected cultivated amaranth for high seed yield and pale grain, natural selection bred Palmer amaranth for raw survival. In 2017 the Weed Science Society of America classified it as the most troublesome weed in the United States. It grows up to 3 inches in a single day, reaches 10 feet tall, produces 500,000 seeds per plant, thrives in heat and drought, and outcompetes corn, soybeans, and cotton for nutrients and water. Fields infested with Palmer amaranth report yield losses of up to 90 percent. In the worst cases, farmers abandon crops entirely.

2004: The First Glyphosate Resistance

In 2004, the first glyphosate-resistant Palmer amaranth was confirmed in Macon County, Georgia. Glyphosate is the active ingredient in Roundup, the most widely used herbicide on Earth. Within a decade, glyphosate-resistant Palmer amaranth had spread across the Southeast cotton belt. Farmers switched to alternative chemistries: 2,4-D, dicamba, glufosinate. Palmer amaranth evolved resistance to all of them. In 2019, glufosinate-resistant populations were confirmed in Arkansas. In 2020, scientists at Kansas State University documented something unprecedented: Palmer amaranth using extrachromosomal circular DNA (eccDNA) to amplify the genes that detoxify herbicides, producing so much of the target enzyme that the herbicide cannot overwhelm the plant. The mechanism had never previously been documented in plants.

The $40 Billion Herbicide Market

The global herbicide market hit roughly $40 billion in 2024. A significant portion of that revenue comes from products targeting Amaranthus species, sold under the agricultural label of pigweeds. Bayer (which now owns Monsanto), Syngenta, Corteva, and BASF all manufacture chemistries designed to kill plants in this genus. The pattern is a closed loop: superweed develops resistance, manufacturer releases new chemistry, superweed develops new resistance, manufacturer releases the next.

The Real Threat: A Crop That Needs Nothing

Conquistadors banned cultivated amaranth because it was too sacred. Modern industrial agriculture fights wild amaranth because it is too successful. The reason Palmer amaranth is unkillable is the same reason cultivated amaranth fed empires: it is adapted to survive. It produces absurd amounts of seed (so farmers can replant from one plant). It thrives in poor soil (so it does not need synthetic nitrogen). It tolerates drought (so it does not need irrigation). It defends itself against pests (so it does not need pesticides). The global nitrogen fertilizer market is roughly $60 billion a year. The global pesticide market exceeded $70 billion in 2024. Amaranth threatens all three revenue streams from a single plant. That is not a flaw of the plant. That is the business case against it.

How to Grow, Harvest & Cook Amaranth

Planting and Identification

Amaranth is one of the easiest grains to grow at the home scale. Direct-sow after the last frost in any sunny spot with reasonably drained soil. The seeds are tiny, so scatter them lightly and rake in. Germination takes 7 to 14 days. The seedlings are recognizable by paired smooth oval leaves, often with a faint reddish tint at the stem base. Mature plants reach 4 to 8 feet tall depending on variety, with Amaranthus cruentus producing crimson-red plumes, Amaranthus hypochondriacus producing dense gold-to-burgundy panicles, and green-grain varieties producing pale plumes that are easier to thresh. The plant tolerates drought, heat, and poor soil. It needs no fertilizer.

Harvesting the Grain

Wait until the plumes feel dry and shed seed when you rub them between your hands, usually 90 to 110 days from sowing. Cut the seed heads into a clean bucket or onto a tarp and rub them between gloved hands or against a screen to release the grain. Winnow in front of a fan or in a steady breeze: the chaff blows away while the heavier seed drops. A single mature plant yields between 50,000 and 100,000 seeds, around half a pound to a full pound of clean grain. Save the largest, cleanest seed from your best plants for next year's planting. No annual seed purchase. No patent. No corporation between you and the next harvest.

Cooking the Grain

The basic ratio is 3 parts water to 1 part amaranth. Bring to a boil, reduce to a simmer, cover, and cook for 20 to 25 minutes until the seeds are tender and the water is absorbed. The texture is similar to porridge, the flavor nutty with a slight pepper note. For breakfast: cook with milk or plant milk, cinnamon, and honey. For a savory side: salt, butter or olive oil, a clove of garlic. For a thicker grain, toast the dry seeds in a hot dry pan for two minutes before adding the water.

Popped Amaranth and Alegría

Heat a dry skillet on medium-high until a single drop of water dances and evaporates. Add a single tablespoon of dry amaranth at a time. Swirl. The seeds will pop within seconds, expanding into miniature white kernels. Larger batches will burn before they pop, so work small. Popped amaranth is the basis of alegría, the traditional Mexican sweet made from popped amaranth bound with honey, agave, or melted piloncillo, pressed into bars, and cut. The same recipe Aztec children ate in Tenochtitlan is still sold in markets across central Mexico today.

The Leaves

Cultivated amaranth produces edible leaves throughout the growing season. Harvest the young leaves and tender shoot tips and cook like spinach. The leaves of weedy Amaranthus retroflexus (redroot pigweed) and Amaranthus blitum are also edible cooked, and have been a famine food and a deliberate vegetable across India, Africa, and the Caribbean for centuries. Like spinach and chard, amaranth leaves contain oxalates and nitrates; cook them rather than eating raw in large quantities, and pour off the cooking water if you are sensitive.

Safety

Amaranth grain is one of the safest staple foods known and has been consumed continuously across the Americas for thousands of years. The leaves contain oxalates and nitrates and should be cooked, not eaten in large raw quantities. Livestock fed unlimited Palmer amaranth foliage can develop nitrate toxicity, which is why farmers eradicate it in pasture; this is not a concern at human dietary scale. Amaranth grain is naturally gluten-free, suitable for people with celiac disease and gluten sensitivity, and has no documented major drug interactions. As with any food crop, harvest from soil you know, away from roadsides, industrial sites, and recently sprayed fields.

Frequently Asked Questions

What is amaranth and why was it banned?

Amaranth (genus Amaranthus) is a pseudo-cereal grain and leafy vegetable that the Aztecs called huauhtli and cultivated as one of the three pillars of Tenochtitlan's food system, alongside corn and beans. Tribute records from Montezuma's reign show 20,000 tons of amaranth flowing into the capital every year from 20 provinces. Aztec priests mixed amaranth seed with sacrificial blood to shape statues of the sun god Huitzilopochtli, which were then broken and shared as a communion. To the Catholic Church arriving with Hernán Cortés, this looked like a savage inversion of the Eucharist. After Tenochtitlan fell on August 13, 1521, Cortés outlawed amaranth cultivation under penalty of death, ordered fields torched and seed stocks burned, and threatened to personally cut off the hands of any farmer caught growing it. The ban held for roughly 400 years.

Is amaranth a complete protein?

Yes. Amaranth contains all nine essential amino acids in significant concentrations: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Total protein is 14 to 19 percent by weight, higher than wheat or rice. The standout is lysine, the limiting amino acid in almost all cereal grains: amaranth contains 5.3 to 6.3 percent lysine, roughly twice the level in wheat and three times the level in corn. The World Health Organization rates amaranth's amino-acid profile as nutritionally equivalent to animal protein, and the Food and Agriculture Organization reports protein digestibility approaching 90 percent.

How do you cook amaranth grain?

Use roughly 3 parts water to 1 part amaranth grain. Bring to a boil, reduce to a simmer, cover, and cook for 20 to 25 minutes until the seeds are tender and the water is absorbed. The texture is similar to porridge, and the natural flavor is nutty with a slight pepper note. For a savory side, add salt and a knob of butter. For breakfast, cook with milk or plant milk, cinnamon, and honey. Amaranth can also be popped like miniature popcorn: heat a dry skillet on medium-high, add a single tablespoon of dry seed at a time, swirl, and the seeds will pop within seconds. Popped amaranth is the basis of alegría, the traditional Mexican sweet made from popped amaranth bound with honey, agave, or piloncillo. The leaves of cultivated amaranth (and of weedy species like Amaranthus retroflexus) are edible cooked like spinach.

What is the difference between cultivated amaranth and Palmer amaranth?

Cultivated amaranth species (Amaranthus cruentus, A. hypochondriacus, A. caudatus) are the grain crops Indigenous farmers in Mesoamerica and the Andes domesticated over thousands of years for high seed yield, large pale or white grain, and tall ornamental flower plumes. Palmer amaranth (Amaranthus palmeri) is a wild cousin native to the southwestern United States and Mexico. The Weed Science Society of America in 2017 called it the most troublesome weed in the United States. It grows up to 3 inches in a single day, reaches 10 feet tall, produces 500,000 seeds per plant, and has evolved resistance to glyphosate (2004 in Georgia), 2,4-D, dicamba, and glufosinate (2019 in Arkansas). In 2020, Kansas State researchers documented Palmer amaranth using extrachromosomal circular DNA to amplify herbicide-detoxifying genes, a resistance mechanism never seen before in plants. Both forms share the same biological strengths: extreme seed production, drought tolerance, and the ability to thrive without inputs.

Why did NASA select amaranth for space missions?

In the 1980s, NASA evaluated crops for closed life-support systems on long-duration missions and selected amaranth for shuttle flights. Three properties drove the decision. First, the nutritional density: 14 to 19 percent protein with the complete amino-acid profile and high lysine that astronauts losing bone density and muscle mass in microgravity specifically need, plus iron, calcium, magnesium, phosphorus, and squalene, an antioxidant otherwise found mainly in shark liver oil. Second, the gluten-free profile, important for crew members with sensitivities. Third, atmospheric regulation: amaranth uses C4 photosynthesis and converts carbon dioxide into oxygen with exceptional efficiency, so the same plants that produce edible leaves and seeds also scrub CO₂ from the recycled cabin air. The grain that fed the Aztec Empire is one of the few crops on Earth that produces complete human nutrition while doubling as a biological air-quality system.