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Plants & People: The Intersection of Botany and Human Experience

Salvia hispanica Phylogenetic Tree

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Salvia hispanica: A Source of Strength Traditionally a key component in Aztec and Mexican culture, chia seeds have been used for centuries for their nutritional, decorative, and medicinal qualities. A common staple in many cultures around the world, these tiny seeds pack a powerful punch and are enjoyed by fitness enthusiasts everywhere. While the seeds themselves are easily recognizable, less well known is their source: a plant known as Salvia hispanica. This flowering, annual herb has a fascinating history and distinctive morphological traits that have evolved over time due to human cultivation. By exploring the myriad ways that this plant has interacted with people over the course of history, we can gain a greater appreciation of how chia seeds have been an important source of strength and inspiration for many. By Joshua Matsuda, Sarah Hoffman, Julia Lindner #Chia
Nomenclatural history
The naming of a species can say a lot about the cultural implications and use of a specific plant in human societies. Salvia hispanica is one of two plants that are commonly known as ‘chia’. The word 'chia' originated in Mesoamerica, being derived from the Nahuatl word ‘chian’ which means oily (Wikipedia authors and editors: EOL, n.d.). In Mayan language, chia was adopted and grew to mean ‘something that makes you strong’ (Raw Edible Plants, 2012). Salvia hispanica was also consumed by many Indigenous tribes in what is today the southwestern United States, each having a different name to denote the species. In Chumash, chia is called "itepesh" or "paj" (Timbrook, 1986).

The Linnean binomial of Salvia hispanica was given by Carolus Linnaeus who "found the plant growing in the new world and confused it with a native plant from Spain" (Valdivia-Lopez, 2015). Salvia, the genus which denotes all of the sages, comes from the latin "salvere" which means to feel healthy (Wikipedia authors and editors: EOL, n.d.).
Evolutionary history
Salvia Hispanica is a member of the Lamiaceae family in the genus Salvia (the sages). The sages are among the largest angiosperm genera housing about 1,000 species. They have become widely distributed across the globe with many economically important species, like rosemary. The genus probably originated in Africa and dispersed first around the Mediterranean, then to the rest of the world. Salvia hispanica belongs to the American subgenus Calosphace and is monophyletic. It is closely related to Salvia mexicana (Mexican bush sage), which is a prized ornamental plant. The Chia’s wild ancestors were short in height (less than 1 m), had striated stem pigmentation of anthocyanin, pubescent and open calyxes, small black seeds (less than 12.0 mg/100 seeds), short inflorescences (less than 15 cm), leaves and light blue corollas that are smaller than the domesticated varieties, and a bushy growth form (Cahill, 2005). Through the domestication process, seed covering color, stem pigmentation, and shattering have been selected for and evolved within the species. Commercially grown chia, through this domestication process, developed geographical and flowering time differences that have formed reproductive barriers between wild types and domesticated varieties (Cahill, 2005). A specific gene selected by certain cultivators, known as "scc," has created a variety harboring white seeds (Lombardo, 2019). This variety also sports "a more stable content of omega-3 fatty acids, especially α-linolenic acid (ALA), than generic Salvia hispanica seeds" (Lombardo, 2019). Variation between cultivars in other aspects besides seed coverings has also developed throughout the domestication process; increased lipid content is something else that has been selected for, which varies from 25% to 40% between varieties (Lombardo, 2019). While the domestication process has developed phenotypically distinct varieties, no actual speciation has occurred between Salvia hispanica's wild ancestors and the commercially grown variety.
Ecology and Life history
Salvia hispanica is widely distributed throughout Central and South America, found growing most effectively from latitudes 22°55’ N to 25°05’ S (U. Šilc, I. Dakskobler, F. Küzmič & B. Vreš, 2020). It is an annual plant and grows most effectively on sandy, well-drained soils with moderate salinity and pH, though it is a relatively tolerant species and can grow on almost any substrate as long as there is good drainage (U. Šilc, I. Dakskobler, F. Küzmič & B. Vreš, 2020). The optimal temperature range is between 16 and 26°C, but it can grow anywhere between 11 and 36°C (U. Šilc, I. Dakskobler, F. Küzmič & B. Vreš, 2020). In its Mesoamerican range, wild populations of Salvia hispanica fare best in wetlands and areas along streams above 1800 m in pine or oak forest (Cahill, 2005). Given its nativity to tropical locations, it is intolerant to freezing conditions.
Morphological description of vegetative attributes
Salvia hispanica is an annual herb, varying widely in height but reaching up to 5’9” tall. Leaves are simple, ovately-shaped, and oppositely arranged, with a clearly defined midrib and second-order veins. Plant morphology has been known to differ between wild-type and domesticated varieties. For instance, wild-type plants tended to have a shorter height (often less than 1 meter tall), shorter inflorescences, smaller leaves, striated stem pigmentation, and a bushier growth form (Cahill, 2005). As chia was domesticated, it is likely that competition with neighboring crops such as maize selected for increased plant height, and that there was also selection for increased branching, which allowed more inflorescences per plant (Cahill, 2005). In addition, average inflorescence length also increased (only the ones at the plant's apex), allowing for greater yields (Cahill, 2005).
Morphological description of reproductive attributes
Salvia hispanica produces tall inflorescence stems extending from the tip of each branch, each containing dozens of individual blue to purple flowers clustered in spiked inflorescence aggregates. The individual flowers have fused corollas and are bilaterally symmetric, and their morphology provides a vessel for bees to effectively pollinate. Each plant is capable of producing over 1,000 seeds over its brief lifetime (Cahill, 2005). These seeds are generally either black or white, and less than a millimeter in length. They are also very hydrophilic, and develop their characteristic gelatinous texture once soaked. As with vegetative morphology, morphology of reproductive features has also been greatly influenced by domestication. Studies have shown that domesticated varieties of chia show clear morphological distinctions such as greater seed mass, lack of seed shattering, and increased range of morphological and phenological diversity, which correlate with various changes in human agricultural practices (Cahill, 2005). In addition, domesticated varieties show more uniform morphology of numerous characters such as height, flowering time, and timing of seed maturation and dispersal. Seeds were also selected for decreased calyx pubescence density; while the pubescence traditionally allowed wild-type varieties to avoid over-hydration, this ended up causing irritation and allergenic effects to the threshers handling the seeds. Also, domesticated varieties of chia tend to have more compact inflorescences (small space between glomeruli), and are more uniform than those of wild populations. Domesticated varieties are also recognizable by the presence of purple on their calyxes; in populations of wild individuals, calyxes only express purple shading when under stressful conditions or towards the end of the plant's life (Cahill, 2005).
Domestication history
While Salvia hispanica’s domestication process and evolution of traits are relatively well understood, the exact time and location of first domestication are unknown due to a lack of archaeobotanical evidence (Cahill. 2005). The soft oily seeds of this herbaceous annual are not easily preserved. However, historical records suggest that it was first cultivated in the region between north-central Mexico and Guatemala, with smaller pockets of cultivation in Nicaragua and southern Honduras (Baron, 2021). Wild populations still exist in Guatemala today, suggesting that cultivated varieties may have been dispersed from this region (Cahill. 2005). Primitive domesticated varieties are rare and are likely to go extinct if the current shift towards agricultural mechanization continues (Cahill. 2005).
Historical Accounts
Despite uncertainty surrounding initial domestication, the historical use and significance of Salvia hispanica is well documented. As early as 3500 B.C., chia was consumed by the Aztec and Mayan peoples of Mesoamerica, and it became a hugely important Mexican cash crop from 1500 to 900 B.C. along with maize and other grains (Baron, 2021). Chia seeds themselves were used for culinary, medicinal, cultural, religious, and artistic purposes. Interestingly, the seeds were offered to the gods in religious ceremonies and given as tribute from conquered nations (Cahill, 2005). Evidence for this comes from Aztec records, which document that 21 of the 38 provincial states gave chia seeds as an annual tribute to rulers (Cahill, 2005).
In the sixteenth century, the Spanish conquest of native civilizations permanently altered Salvia hispanica’s importance as a domesticated crop (Cahill, 2005). Spanish codices from the early 1500’s document large plots of land devoted to chia cultivation, but this cultivation plummeted quickly as European crops were brought in and Indigenous populations dwindled (Valdivia-López, 2015). For Spanish colonists, consumption of the crop was mainly limited to agua de chia, a drink made from chia seeds (Valdivia-López, 2015). Today, many traditional uses of chia have been lost due to the erasure of colonialism.
Cultivation History
Modern-day chia cultivation looks very different from traditional Aztec and Mayan cultivation. Over sixty varieties are grown today, primarily in Bolivia, Australia, Argentina, and Ecuador (Baron, 2021). Bolivia and Australia are the largest commercial growers of chia, whereas Mexico, Nicaragua, and Guatemala see more small-scale, local production (Baron, 2021). Salvia hispanica grows best between 23 degrees north and south of the equator, and it has never been genetically modified since it is relatively easy to cultivate, ship, and store (Baron, 2021).
While chia cultivation is largely mechanized today, it was traditionally done by hand. According to reports written by Hernández Gómez in the Mexican state of Guerrero, some traditional growers would toss seeds into the wind, without preparing the soil at all (Cahill, 2005). More recently, small-scale farmers such as Jesus de Latorre Guiterrez of Jalisco used machines to punch small holes in furrows, drop seeds in each, and leave them uncovered by soil (Cahill, 2005). In general, once Salvia hispanica begins flowering and the seeds emerge, the seed heads are removed and shaken in order to release the tiny seeds themselves (Cahill, 2005). The seeds are then placed in sacks or baskets for cleaning, without a need for preservatives. Due to culinary preferences and superstitions, black seeds were selectively harvested over white seeds, which allowed white-seed varieties to expand their populations at a higher rate (Cahill, 2005).
Nutritional Value and Part of the Plant Consumed
Chia seeds have long been consumed across many cultures for their various nutritional and associated health benefits. These seeds are known for their high oil content; each seed may contain up to 30% extractable oil, which is rich in omega-3 fatty acids. These fatty acids have been attributed to various health benefits, including increased cardiovascular health, lowered cholesterol, decreased inflammation, blood pressure regulation, and reduced risk of cardiovascular mortality (Harvard, 2022). The seeds are “true proteins,” containing all 9 of the essential amino acids not naturally produced by the human body, and contain trace amounts of other nutrients such as calcium, phosphorus, zinc, and copper. They are also completely gluten-free, and contain many “phytonutrients,” which are biologically-produced chemicals containing compounds such as quercetin, kaempferol, myricetin, chlorogenic acid, and caffeic acid. These phytonutrients benefit both plants and human consumers; plants receive protection from insects, disease, drought, injury, heat, UV radiation, and various pollutants, while humans are benefitted through lowered risk of cancer, diabetes, cardiovascular disease, and hypertension (Harvard, 2022). In addition, chia seeds contain fibers making up the characteristic “gluey” texture of the seeds; these fibers are known to lower LDL cholesterol levels, slow digestion, promote satiety, and prevent spikes in blood sugar following meals (Harvard, 2022).
Chia may be consumed in a variety of ways, including entire seeds, ground seed flour, seed mucilage, and extracted seed oil. Many traditional Mesoamerican dishes have incorporated chia, including Pinole, an Aztec dish in which the seeds are roasted, milled into flour, and then combined with corn flour and water. The resulting porridge is eaten as-is. They could also shape the chia into cakes to be cooked over an open fire.
Chia is still widely consumed today. While chia seeds contribute very little flavor, they are commonly added to beverages, baked goods, cereals, crackers, salad dressings, and marinades to provide a boost in nutritional value (Harvard, 2022). The seeds are also used to replace eggs (moistened seeds and seed powder will thicken to the consistency of a scrambled egg) and to make the dessert “chia pudding,” and chia sprouts are commonly used as garnishes on salads and sandwiches.
Human Experience
The nutritious seeds of Salvia hispanica were a key staple of indigenous communities beginning 4,500 years ago throughout Mesoamerica; in some communities, chia even surpassed maize as a key component of local diets (U. Šilc, I. Dakskobler, F. Küzmič & B. Vreš, 2020). This long and culturally-significant history is reflected in a collection of at least 105 accounts of ethnobotanical use from sources prior to 1600 CE and 79 accounts from sources after 1600 CE (Garner-Wizard et al., 2004). These include codices, writings of naturalists, ethnographic studies, and preserved specimens containing ethnobotanical information (Garner-Wizard et al., 2004). Many of these also depict medicinal uses, such as utilizing the infusion of chia seeds to "enhance the uptake of other medicines" (Garner-Wizard et al., 2004). Culinary uses were also heavily documented, as Salvia hispanica was an important element in pre-Columbian foods and beverages in across Mesoamerica (Garner-Wizard et al., 2004). For many, Chia came to be known as an incredible source of strength. The Tarahumara tribe, known for their incredible feats of running, consumed chia in a drink called Iskiate, which is a mix of chia seeds, lemon, and water. After consuming this beverage, it has been traditionally said that an individual is "now able to run hundreds of miles" (Chia Seed History and Origin, 2016). As mentioned above, the Aztecs also consumed chia in various dishes such as Pinole, which involved the roasting and milling of the seeds, creating a porridge that could be shaped into cakes and heated over a fire. The Aztecs also pressed the seeds for oil, using it as a moisturizer and in face and body paints.

In Aztec society, chia was so important that its cultivation is included within the Codex Mendoza, an Aztec manuscript written in 1541 that contains a detailed history of Aztec rulers, conquests, and descriptions of Aztec daily life. Within the Codex, it was documented that “the city of Tenochtitlan received as tributes from conquered nations a minimum of 6,360 tons of maize, 4,410 tons of beans, 4,410 tons of chia, and 3,780 tons of amaranth, annually,” suggesting that chia was essentially treated as a form of currency (azCHIA, 2018).
While chia was a highly utilized commodity in Mesoamerica, chia seeds did not become a global phenomenon until much more recently. Chia was brought to the US in 1977, through the commercialization of chia pets. The “inventor” of chia pets, Joe Pedott, appropriated the use of chia sprouts by Oaxacan artists after visiting the city, in which chia sprouts are widely used in ornamental gardens throughout the area. He mirrored the terracotta figurines and presented them to American audiences who, because of the catchy marketing slogan, immediately took to this new product. Despite this widespread integration of chia into American culture, chia seeds were not widely consumed outside of Mesoamerica until the 2010s, when health food sectors began to market chia as a superfood. This superfood classification is the most dominating sentiment surrounding chia today. Chia has become widely available in grocery stores, being consumed for its proposed health benefits in smoothies, puddings, and oatmeal, where it is marketed for its nutritional content.
References
azCHIA. (2018). Chia History - An Ancient Crop. https://waynecoates.com/AZchiaInfo/chia-seeds-history/
Baron, M. (2021). A History Of Chia Seeds. Wholesale Nuts And Dried Fruit. https://wholesalenutsanddriedfruit.com/a-history-of-chia-seeds/
Cahill, J. P. (2005). Human Selection and Domestication of Chia (Salvia hispanica L.). Journal of Ethnobiology, 25(2), 155–174. https://doi.org/10.2993/0278-0771(2005)25[155:HSADOC]2.0.CO;2
Chia Seed History and Origin. (2016). Grand Teton Ancient Grains. Retrieved May 26, 2022, from https://www.ancientgrains.com/black-chia-seeds/chia-seed-history-and-origin/
Garner-Wizard, M., Henson, S., Hoots, D., & Robbins, S. (2004). Chia (Salvia hispanica) and Its Long History of Use Reveals Future Potential - American Botanical Council. American Botanical Council. https://www.herbalgram.org/resources/herbclip/issues/bin_269/review44017/
Harvard T.H. Chan School of Public Health. (2022). Chia seeds. The Nutrition Source. Retrieved May 24, 2022, from https://www.hsph.harvard.edu/nutritionsource/food-features/chia-seeds/
Lombardo, Y. B., Creus, A., Oliva, M. E., & Chicco, A. (2019). Effects of dietary Salba (Salvia hispanica L.) on glucose metabolism in an experimental model of dyslipidemia and insulin resistance. Molecular Nutrition: Carbohydrates, 303–318. https://doi.org/10.1016/b978-0-12-849886-6.00008-2
Raw Edible Plants. (2012). Chia (Salvia hispanica). Retrieved May 24, 2022, from http://rawedibleplants.blogspot.com/2012/04/chia-salvia-hispanica.html
Timbrook, J. (1986). Chia and the Chumash: A Reconsideration of Sage Seeds in Southern California. Journal of California and Great Basin Anthropology, 8(1), 50–64. https://escholarship.org/uc/item/7d33504g
U. Šilc, I. Dakskobler, F. Küzmič & B. Vreš (2020) Salvia hispanica (chia) – from nutritional additive to potential invasive species, Botany Letters, 167:2, 255-264, DOI: 10.1080/23818107.2019.1700550
Valdivia-López, M. N., & Tecante, A. (2015). Chia (Salvia hispanica). Advances in Food and Nutrition Research, 53–75. https://doi.org/10.1016/bs.afnr.2015.06.002
Wikipedia authors and editors. (n.d.). Spanish sage: Salvia Hispanica L. - Encyclopedia of Life. The Encyclopedia of Life by National Museum of Natural History. Retrieved May 24, 2022, from https://eol.org/pages/578468/articles#endnote_Sahagun69a