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Walter H. Lewis: 1930 – 2020


Walter H. Lewis, PhD, a renowned botanist whose expertise spanned the flora of multiple continents and disciplines as disparate as cytology and pharmacognosy, passed away peacefully in his home in St. Louis, Missouri, on November 17, 2020. He was 90 years old.

He is most widely known for the 1977 seminal book Medical Botany: Plants Affecting Man’s Health (Wiley), cowritten with his wife and collaborator of 63 years, Memory Elvin-Lewis, PhD. At the time of publication, few books on this topic were as approachable to the public. Its publication coincided with growing consumer interest in herbal medicine and the herbal supplement industry in the United States, and it quickly became a standard reference for learning about the science behind medicinal plants. In his 1979 review for the Journal of Natural Products, Paul Schiff, Jr., PhD, noted: “A virtual plethora of subjects is discussed…. [T]he authors have assembled a large number of references on widely diverse subjects and presented a great deal of interesting material in an easily readable fashion.”1 The first edition sold more than 20,000 copies and in 2003 was extensively revised and republished under the title Medical Botany: Plants Affecting Human Health.

“Walter was a mentor, colleague, and friend,” wrote American Botanical Council (ABC) Founder and Executive Director Mark Blumenthal (email, January 7, 2021). “He was a consummate gentleman, always very pleasant and courteous. He was one of the first academic experts on medicinal plants I ever met, and I first encountered him at the first Herb Trade Association Herb Symposium in 1977. In the late 1970s and early 1980s, the first edition of Medical Botany was one of my most-used references, and I was honored when Walter invited me to write a blurb for the 2003 revision. Over the years, Walter was always available, cooperative, and responsive to requests for [his] expert assistance. His death is a huge loss to the botanical medicine academic community in the United States and worldwide.”

As a professor of biology at Washington University in St. Louis from 1964 to 2000, he taught a popular undergraduate course based on his book and not only instilled in his students knowledge of useful plants, but also engrossed them with tales of his adventures collecting medicinal plants from around the world. His last medical botany class at Washington University is vividly remembered by students who witnessed him arrive dramatically dressed in the style of the Jivaroan people from the Amazon basin, toting a dart gun; whether curare poison was painted on the dart tip is subject to debate.

Lewis’ last doctoral student, Steven Casper, PhD, now a scientist at the US Food and Drug Administration, recalled (email, December 10, 2020): “His medical botany class was extremely popular, and the students were fascinated by the course and Dr. Lewis’ amazing stories of his travels and research. He was always willing to talk with, help, and guide students. He was one of the rare gentlemen scholars and is greatly missed.”

Joseph Jez, PhD, chair of biology at Washington University, wrote (email, December 11, 2020): “Walter was a great example of a scientist who truly explored, following the data and ideas from the bench into the rainforest. He will be missed by all.”

Lewis was born on June 26, 1930, in Ottawa, Ontario, and first became interested in plants as a child in Victoria, British Columbia, where he was fond of growing plants. For his 12th birthday he asked for and received a greenhouse, learned to grow roses from his uncle, and started a small business selling them locally. Although his parents encouraged him to pursue dentistry (interestingly, his wife is a dental microbiologist and ethnobotanist), his passion for botany would be a guiding force throughout his life. After completing his undergraduate degree in biology at the University of British Columbia, he immediately began his doctoral work in plant biology at the University of Virginia as a DuPont fellow. Under the mentorship of Walter Flory, PhD, Lewis revised the genus Rosa (Rosaceae), and this thesis was recognized as one of the best in the state by receiving the J. Shelton Horsley Research Award from the Virginia Academy of Science in 1957.

Lewis published more than 300 papers about plants, which ranged from classical taxonomy, cytology, ethnobotany, phytochemistry, and ecology. Sir Ghillean Prance, DPhil, former director of the Royal Botanic Gardens, Kew, wrote (email to M. Elvin-Lewis, January 12, 2021): “I am really impressed with Walter’s publication record and am glad to have this bibliography about so many different topics. … Walter will be missed by many people and has made a highly significant contribution to botany.”

Late in his career, Lewis returned to his original interest in the genus Rosa. He helped revise the section Rosa in the Flora of North America, and the ninth volume of this flora (Oxford University Press, 2014) is dedicated to him. In 2013, he was named Rosarian of the Year by an affiliate of the American Rose Society. He also maintained a unique collection of native American roses at his large home garden in St. Louis. In one of his final rose publications in 2016, he described a new species, Rosa memoryae, which is native to Texas and named in honor of his beloved wife.2

Lewis’ field work in botany took him to many near and faraway lands including Africa, North and South America, and Asia. In his role as the director of the herbarium at the Missouri Botanical Garden, he was the editor of the Flora of Panama (1965-1970). His work on American ginseng (Panax quinquefolius, Araliaceae) conservation led him to be among the first American scientists to travel to mainland China in the 1970s, where he participated in the First National Wu-Cha (Acanthopanax)* Symposium in Harbin, China, in 1978. This groundbreaking international interaction, only six years after US President Richard Nixon’s historic trip in 1972, was covered by NBC News. At the symposium, Lewis presented a talk about his work on wild and cultivated populations of American ginseng.3

Lewis’ work with his wife in West Africa in the mid-1970s laid the groundwork for their long-standing collaboration in the field of ethnobotany. As an ethnobotanist, Lewis was most well-known for his work among the native peoples of Peru. For more than 20 years, he and Elvin-Lewis worked as a team conducting research on the plants used by the Achual and other native peoples of that area. He was awarded a highly competitive grant from the International Cooperative Biodiversity Groups (ICBG) Program of the National Institutes of Health to study ethnobotany in the Andean tropical rainforests of Peru.

Gordon Cragg, PhD, who headed this program at the National Cancer Institute, noted that Lewis’ legacy lives on through his ICBG-sponsored work (email, December 8, 2020): “Almost 4,000 plant species were collected, including a large number prescreened for human use by the Aguaruna themselves, and it is significant that these provided higher frequencies of bioactive secondary metabolites than those found in the flora as a whole. Since the cessation of Walter’s ICBG grant support in the early 2000s, this invaluable plant collection has continued to be studied by most of the original team members and has been a source of a range of potential new anticancer, anti-infective, and wound-healing agents.”

Michael J. Balick, PhD, vice president for botanical science and director and philecology curator of the Institute of Economic Botany at the New York Botanical Garden and ABC Board of Trustees member, wrote (email to S. Casper, December 11, 2020): “As a graduate student attending one of my first meetings of the Society for Economic Botany, I was understandably intimidated by all of the luminaries present in the group. I remember Walter Lewis, who was a friend of my advisor Richard Evans Schultes, coming over and introducing himself, inquiring about my work and telling me about his latest tropical expedition. That was emblematic of Walter: to care about the next generation of ethnobotanists and be helpful to all.”

I was a doctoral student at Washington University in St. Louis and was mentored by both Lewis and Elvin-Lewis in my research on medicinal plants. Lewis was a gentleman and a scholar in the very essence of that phrase. His passion for botany was evident from the first time I met him. I conducted field work with him in Amazonia and learned not only about botany and science, but also how to work effectively with people from different backgrounds. In 2019, I traveled with Lewis, his wife, and Steven Casper to Ontario to be part of Elvin-Lewis’ tribute as an outstanding Canadian scientist. While his mind was obviously impacted by Alzheimer’s disease, he enjoyed engaging with people and was as polite and kind as I always remember him. He also remained passionate about plants, examining the local flora as we walked the streets of Guelph together.

Walter Lewis is survived by his wife, Memory Elvin-Lewis; his two children, Walter Jr. (Joanna Watt) and Memoria (Trevor Morse); and three grandchildren, Florence, Lilian, and Leander. The family is planning a home memorial service in June 2021 when the wild rose collection in his garden will be in full bloom.

Edward Kennelly, PhD, is a professor of biological sciences at Lehman College, City University of New York. He received his PhD in biology from Washington University in St. Louis in 1993 under the mentorship of Walter Lewis and Memory Elvin-Lewis.


  1. Schiff PL. Book Review: Medical Botany — Plants Affecting Man’s Health. Journal of Natural Products. 1979;42(1):130.
  2. Lewis WH. Nomenclatural novelties in Rosa recognized in North America. Novon. 2016;25(1):f.2.
  3. Lewis WH. First National Wu-Cha Symposium. The American Society of Pharmacognosy Newsletter. 1979;16(1):15.