Ynés Mexía: Botanical Groundbreaker

The Missouri Botanical Garden Herbarium is more than just a research tool for botanists; it’s also a window into history. Each specimen tells a story—connecting people, plants, and places. With more than 7 million specimens, the Garden Herbarium has some amazing stories to tell.

The Herbarium can tell us about the early career of groundbreaking Black botanist George Washington Carver—or Anna Isabel Mulford, the first student to earn a PhD at Washington University. The Herbarium also gives us a glimpse at the prolific plant collecting of a woman whose work nearly a century ago is still leading to botanical discoveries today.

Ynés Mexía

The career of Ynés Mexía is remarkable for many reasons. Her collections—numbering nearly 150,000—led to the discovery of dozens of new species and greatly expanded the botanical understanding of the plants of Mexico and parts of South America.

More notable still, she made these contributions after picking up botany as a field of study for the first time in her 50s. It is also worth pointing out Mexía was doing all this at a time (the 1920s and 30s) when botany was a male-dominated discipline and women were generally discouraged from participating.

Mexía was born in Washington DC in 1870, and spent a large part of her childhood in the area of what is today Mexia, Texas. She also spent many years operating a family ranch in Mexico, before moving to San Francisco and joining the Sierra Club. And in 1921, at the age of 51, she enrolled at the University of California Berkeley to study botany.

The collections Mexía would make during her botanical career were sent to several herbaria across the United States, including the Missouri Botanical Garden. These collections, along with her field notes and subsequent writings provide us with amazing insight into the life of this botanical groundbreaker.

Video: UNLADYLIKE2020 profiles Ynés Mexía

The Lure of the Unknown

Mexía set off on her first solo collecting trip, to western Mexico, in 1926. “As I had never been in this region before,” she would later write, “I found the luxuriance of vegetation actually embarrassing. It was hard to know where to begin to collect and still harder to know when to stop.”

Her strategy, as she recounts in Botanical Trails in Old Mexico—The Lure of the Unknown, was to collect in remote areas where others had likely never explored. It paid off just days into her 1926 trip, yielding a new species named in her honor Daphnopsis mexiae.

Her notes highlight the importance of local knowledge, and show that species “new to science” are not necessarily new to human experience. Such is the case with Euphorbia mexiae, which Mexía notes was called “Hierba del arlomo” by the locals and used to treat insect bites.

Of the 900+ collections from her trip, more than 50 would become what is known as a type specimen. Meaning those specimens correspond directly to the description of a new species. Nine of the new species collected by Mexía on that trip would bear her name, and one would represent an entirely new genus—Mexianthus mexicanus.

Three Thousand Miles Up the Amazon

Mexía’s most fruitful and adventurous collecting trip began in 1929. Her goal—to follow the Amazon River from its mouth at the Atlantic Ocean all the way to its source in the Andes mountains. Before venturing up the river, Mexía spent more than a year collecting in the mountains of the Brazilian state of Minas Gerais.

Within days of her arrival in-country, Mexía was already collecting plants that would turn out to be new species—such as a beautiful red and purple Fuchsia bracelinae, and a tree species that would bear her name, Diospyros mexiae.

In August 1931, Mexía set off from the east coast of Brazil up the Amazon River toward Peru. “Every foot of terra firma is heavily wooded, and these forests of the Lower Amazon are truly magnificent,” she would later write about her view of the landscape from the riverboat. Her tone changed after having the opportunity to go ashore.

“Beautiful as is the forest seen from the river, it is repelling to enter. The canopy is so dense that it cuts off all sunlight, prohibiting undergrowth. There are no trails; it is dark and dank, with crowding tree-trunks, tangling lianas, rotting logs everywhere, and oozy, treacherous soil.”

Ynés Mexía

Along the way Mexía and her expedition would trade the luxury of the riverboat for the practicality of dug-out canoes, and shift from the Amazon River to the Marañon River—the mainstream source of the Amazon flowing down from the Andes Mountains. As they made their way further west Mexía recalls being tracked by jaguars and confronted by indigenous tribes armed with spears.

Mexía set up camp where the Rio Santiago meets the Marañon River, near a deep gorge known as the Pongo de Manseriche. She spent three months botanizing this area, “marooned” as she would describe it, by the heavy rains and flooding. But it afforded her the opportunity to collect dozens of plants that would later be described as new species—including about a dozen new species of Piper, the botanical genus to which belongs black pepper.

Three Piper specimens collected by Mexía at Pongo de Manseriche and described as new species by former Garden Director Dr. William Trelease.

When the rains subsided, Mexía traveled by raft back through the Pongo de Manseriche. She parted ways with her plant collection in the city of Iquitos—her plant collection traveling down the Amazon to California via the Panama Canal. Mexía herself would travel west by plane, train, and automobile (and mule) to fulfill her wish to cross South America at its widest point.

A Lasting Botanical Legacy

Mexía would return to the field several more times in her career—collecting in places such as Ecuador, Chile, Argentina, and Peru. The Missouri Botanical Garden Herbarium contains specimens collected in May of 1938, just two months before Mexía would pass away from an illness.

Although her career was-short lived, Mexía’s mark on the field of botany is profound and lasting. Some of the plants she collected decades ago are still being studied and even described as new species by Missouri Botanical Garden botanists.

The late Alwyn Gentry would use a collection made during Mexía’s time in Brazil to name a new species, Arrabidaea ornithophila, in 1976.

Charlotte Taylor, a leading expert on plants of the coffee family (Rubiaceae), has named two new species after Mexía. Sixty-one years after it was collected near Pongo de Manseriche in 1932, Palicourea yneziae was described by Taylor as a new species. In 2014, Taylor would describe another new species, Coussarea mexiae, from a collection Mexía made in Bolivia in 1935.

And as recently as 2019, aroid expert Tom Croat would describe Anthurium mexiae. The plant was first collected by Mexía in the coastal town of Esmereldas, Ecuador, in 1936.

Mexía’s collections are, to this day, helping to enhance our understanding of earth’s plant life. By preserving her work in the Garden Herbarium, we are able to study and build upon that legacy.

Cassidy Moody
Senior Digital Media Specialist

Cover photo from The Bancroft Library, University of California, Berkeley

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