Science Heroes: Ynés Mexía

Imagine field journals piled high with sheaves of plant specimens, expertly preserved on special paper to resist the decay of time, their distinctive flowers and varied fronds, encouraged from their dimensional fullness and pressed flat to maximize space . . .

These plant specimens painstakingly, delicately collected and cataloged, are just one legacy of Mexican-American botanist Ynés Mexía (ee-NEZ MEKS-ee-ya).  Just as enduring a legacy is her demonstration that no environment is too wild for a woman field biologist, and that no age is too old to embark on a career as a scientist.

Portrait of Ynés Mexía from The Bancroft Library, University of California, Berkeley [Source].

Mexía lived in a time and culture in which it was inappropriate for women to travel alone, never mind do the adventurous and “unfeminine” work of a scientific explorer. Perhaps, then, it is unsurprising that she joined her profession late in life.  She was born in 1870 in Washington, D.C. where her father worked as a Mexican diplomat, and she lived in the United States until age nine when her family moved back to Mexico. Shortly thereafter, Mexía’s parents separated and she was sent to boarding school.  Mexía experienced depression and loneliness in school.  During her early adulthood she helped her father manage his household and ranch, taking over after his death, and lived through two unhappy marriages.  Burdened by physical and mental health problems, in 1909, 39-year-old Mexía moved to San Francisco to seek psychiatric treatment.

Photograph of Ynés Mexía [Source].

By all accounts, the move and the fresh scenery it provided was a life-changer for Mexía.  She found comfort in nature and loved the landscapes of northern California, taking special delight in the redwood forests.  Home to some of the largest and oldest living beings on earth, redwood forests were in rapid decline in the early 1900s, threatened by logging and expanding industrialization.  Mexía became active in the environmental conservation movement and joined the Sierra Club and Save the Redwoods League to help protect these ecosystems.  Her conservation involvement led Mexía to pursue further education at 51-years-old: Mexía enrolled at University of California, Berkeley in 1921 and began taking classes in science and natural history.  There she was introduced to botany and discovered a new love for collecting and classifying plants. 

Mexía was a minority in science in multiple respects: she was a woman, a Latina, and older than many of her peers.  Furthermore, women biologists at the time were encouraged to pursue studies in the relative safety of libraries and laboratories.  However, Mexía defied this cultural limitation.  She joined an expedition to Sinaloa, Mexico sponsored by Stanford University in 1925; during that trip Mexía collected over 1,500 plant specimens, each of which she would dry and press on special paper, taking careful notes to describe the plant and its surroundings.  One of the specimens, Mimosa mexiae, is a flowering plant in the pea family and was the first species to be named in her honor; like many of the plants she collected, this species had never before been described by scientists.  This expedition to Sinaloa was the start of a highly productive career in which Mexía traversed continents, rode horseback, camped outside, and proved that women are fully capable of doing the tough, rugged work of field biology.

One of Mexía’s 150,000 specimens; she collected this sample of Mexianthus mexicanus B.L. Rob. in 1926 from Southwest Mexico [Source].

Why do scientists collect specimens?

Biologists collect samples of plants, animals, fungi, and even microorganisms which are identified, preserved, and often stored in museums.  These specimens are very important for several reasons: (1) they serve as models of particular species, so that other samples can be compared to the original “type” specimens to determine if they are the same or deserving of a new species designation; (2) they provide records of the flora and fauna of the past, allowing future researchers to determine how environments and organisms have changed over time; (3) researchers can gather much information from preserved specimens—including morphology, geographic origins, and even genetic material (DNA)—that can be used to answer scientific questions. [See above image]

Pen and ink drawing of Begonia ynesiae L.B. Sm. & Wassh., one of the species collected by and named after Ynés Mexía [Source].

In one of her letters Mexía wrote, “A well-known collector and explorer stated very positively that ‘it was impossible for a woman to travel alone in Latin America.’ I decided that if I wanted to become better acquainted with the South American Continent the best way would be to make my way right across it.”  And that is exactly what she did.  During her 50s and 60s Mexía embarked on a total of eight collecting trips ranging from several months to three years long.  She preferred to work alone, but would often hire local guides.  Her extensive travels through Latin and South America took her to Brazil, Peru, Ecuador, Bolivia, Argentina, Chile, and different regions of Mexico.  Mexía traveled by canoe up the Amazon River from its delta to its source in the Andes Mountains—an amazing journey lasting 3 years and nearly 3,000 miles.  Along the way she collected ~65,000 specimens and briefly crossed paths with Agnes M. Chase, another early female botanist who specialized in grasses.  Mexía was also the first scientist to collect plant specimens from land that is now Denali National Park in Alaska.  Many of her specimens were sent back to Berkeley to the California Academy of Sciences—by steamship!

“In all my travels I’ve never been attacked by a wild animal, lost my way or caught a disease… I don’t think there’s any place in the world where a woman can’t venture.”

– Ynés Mexía

Mexía’s 13-year professional career was short compared to many of her peers but prolific, yielding around 150,000 specimens and documenting around 50 species that were new to science.  Mexía gave occasional lectures, including many of her own photographs from her travels, and she published several accounts of her expeditions in journals such as the Sierra Club Bulletin and the California Botanical Society’s Madrono. Sadly, Mexía became sick on her last field trip to Mexico in 1938 and died of cancer later that year. The impact of Mexía’s conservation work and collection trips was both personal and professional: Mexía once said “I have a job where I produce something real and lasting.” Not only did she pave the way for future women scientists to don their field clothes and traverse the muddy and exciting paths of field biology, Mexía’s collections continue to be studied and provide novel information about the floral diversity of the regions she explored.


Have a Young Explorer that would benefit from knowing this Science Hero? Head over to the Sci Hero column on Animal Adventure Thursdays for printable Sci Hero Trading Cards featuring the Sci Hero’s “origin story” and super powers.

Check out this short film about Ynés Mexía and accompanying lesson ideas for teachers!

Ynés Mexía is featured in: Science Superstars: 30 Brilliant Women who Changed the World by Jennifer Calvert (St. Martin’s Publishing Group, 2021)


[1] Mexía, Y. & Copeland, E.B. (1932). Brazilian Ferns Collected by Ynés Mexía. Editor University Press.

[2] Mexía, Y. (1933) Three Thousand Miles up the Amazon. Sierra Club Bulletin, 18(1), 88–96.

[3] Mexía, Y. (1937) Camping on the Equator. Sierra Club Bulletin, 22(1), 85–91.

Cover Illustration by Rafael Lopez from the book BRAVO! Poems about Amazing Hispanics (Henry Holt and Co.); used with permission from the artist [Source].

Jessica Schaefer is a PhD student in the Animal Behavior Graduate Group at UC Davis. She studies the behavior and mating systems of creatures from limpets to lizards to birds. Jessica loves poking around tidepools and looking at coastal animals and algae.

Additional References:

Bracelin, H. P. (1938). Ynés Mexía. Madroño, 4(8): 273–275. Retreived from

Kiernan, E. (February 2015). Late Bloomer: The Short, Prolific Career of Ynés Mexía. Science Talk Archive, New York Botanical Garden. Retrieved from

Radcliffe, J.  (n.d.). Ynés Mexía (1870-1938). California Academy of Sciences. Retrieved from

U.S. National Park Service. (n.d.). Ynés Mexía. Retrieved from

UNLADYLIKE2020. (2020). Ynés Mexía. Unladylike Productions, LLC. Retrieved from

Verma, M. (August 2021). Adventure, Botany, & Conservation: The ABCs of Ynés Mexía. Picture a Scientist. Retrieved from

[Edited by Karli Chudeau]

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