Peter M. Ray, biologist with a passion for winemaking, has died at 94

Peter M. Ray, professor emeritus of biology in the Stanford School of Humanities and Sciences (H&S), accomplished scientist, and much-admired mentor who also taught students the ways of wine, died May 19, 2026. He was 94.

As a professor, Ray published a series of pioneering papers on the biochemistry and physiology of plant cell growth. He was particularly interested in the plant hormone known as auxin, and he pioneered several techniques for detecting, isolating, and studying it and other plant hormones. He was also an enthusiastic oenophile, thanks to his adoptive father, the vintner Martin Ray, who introduced him to the pleasures of grape growing and winemaking. 

“Peter followed in his father’s footsteps by being a master vintner,” said H. Craig Heller, the Lorry I. Lokey/Business Wire Professor and professor of biology in H&S. “Many of us have great memories of Peter generously sharing his extensive knowledge and appreciation of wine through recruiting us to his vineyard in the foothills to pick grapes, to his evening wine courses, and to many opportunities to experience truly great wines. Sometimes those evenings ended with Peter playing his concertina and singing ballads originating from faraway wine regions. 

“After Peter retired and moved to Alaska, he would return periodically to deal with vineyard work, and on those visits, he would share with me his continuing interests in plant biology. Those interests usually began with simple observations. For example, when it is far below freezing in the Arctic, why don’t twigs of the brush break when weighed down by snow? Simple but clever experiments would follow that reflected Peter’s scientific talents that ranged from the curiosity of a naturalist to the rigor of a physicist. I feel very fortunate to have had Peter Ray as a colleague and a wine-loving friend.”

A pioneering biologist and a hands-off mentor

Ray joined Stanford as a professor in 1968 and was still publishing in 2024, when he was 92. Early on, he was approached by his alma mater, Harvard, about a job there, and when he turned it down, he was told that such an opportunity would not come around again. His witty response: “Well, then I won’t have to decline your offer twice.” 

On the Farm, Ray might be best known for teaching the Biology Department’s core course on plant and animal physiology. That course, co-taught with Heller, enabled students to compare and contrast the mechanisms whereby plants and animals solve similar problems presented to them by the environment. Ray’s teaching is reflected in his book The Living Plant (Holt, Rinehart & Winston, 1963), a classic that is still available. He also wrote the textbook Botany (Saunders College Publishing, 1983) with his second wife, Sara Fultz, an adjunct professor at Stanford. In addition to books, he published over 50 papers that helped define such topics as hormone-induced biochemical changes in the cell walls of plants. 

In 1971, Ray’s work was recognized nationally when he received the inaugural Charles Albert Shull Award from the American Society of Plant Physiologists. Still given today, the award honors early-career scientists for outstanding investigations in plant biology. 

“Peter Ray was a brilliant researcher who made extraordinary contributions to our understanding of plant growth and plant function,” said Sharon R. Long, the William C. Steere, Jr. - Pfizer Inc. Professor of Biological Sciences in H&S. “The hallmarks of his work were his quantitative approach, creative ideas, and extraordinary technical skill and care. He was especially known for his work on plant cell walls and hormone action. He was also a dedicated teacher whose rigorous, math-heavy advanced class on plant physiology was described by students as the ‘hardest course you’ll ever love.’”

Another course of Ray’s might have been the easiest his students ever loved: a weekly lecture devoted to wine, finished with blind tastings. His students included faculty, staff, and postdocs, and Ray typically featured a specific type of European wine, with examples to demonstrate each bottle’s unique attributes. As his wife, Syndonia “Donie” Bret-Harte, noted in an unpublished biography, the course was “a huge hit with the Stanford community, with many people taking it more than once.”

And while that course was unofficial, it also demonstrated Ray’s passion for sharing knowledge with those who shared his enthusiasms, whether for wine or for plant biology.

“Peter was a hands-off mentor, letting his students decide what they wanted to work on, and once they decided, he provided complete support. There was never a boring moment when you sat down with him to discuss the results or, for that matter, any topic,” wrote Ray’s penultimate and last postdocs, Peter Ulvskov, professor of plant biology at the University of Copenhagen, and Kanwarpal Dhugga, a former DuPont scientist, in a tribute for the journal Plant Physiology. 

A childhood love of plants

Ray was born Peter Martin Kamb in 1931 in San José, California, along with his twin brother, Walter Barclay. Ray and his brother were so close that they spoke their own made-up language, which no one else could understand.

His parents separated in 1936, and he eventually enrolled in a private boarding school where students hiked and explored. While there, Ray received a book called Pacific Coast Trees, which introduced him to a love of botany. At age 12, he created a plant list that is still archived at Harvard, where Ray eventually received his doctorate in plant physiology in 1955. During his graduate studies, he had a summer field assistant job with renowned ecologist Robert H. Whittaker and worked identifying plants and characterizing their communities in the Siskiyou Mountains in southern Oregon.

Ray attended the University of California, Berkeley as an undergraduate. Around the same time, his mother, Eleanor, married the vintner Martin Ray, who adopted Eleanor’s children. Peter Kamb changed his last name, despite having reached adulthood, and his adoptive father and the Ray vineyard proved to be an enormous influence on him. 

Ray had been married twice, with children, when he met Bret-Harte. They married in 1997; shortly before that, Ray had begun spending time at the Toolik Field Station in Alaska, where Bret-Harte was doing field work. The couple ultimately moved to Fairbanks, Alaska, in 1998 and stayed there the rest of his life, with Ray commuting to Stanford (and his winery) for work. (Their time together there was captured in a memorable salon.com article, which chronicled their documentation of climate change and its effects on the state’s tundra.)

Ray retired from Stanford in 1999 but continued to teach at the university until 2003 and to work at the vineyard until 2023. He also assisted Bret-Harte in her research, collecting plant specimens and developing lab exercises for her students at the University of Alaska Fairbanks. He stayed fit—running, skiing, and lifting weights—into his 80s and continued writing and publishing into his 90s. 

He is survived by his wife, Syndonia; his sons, Marty and Nigel; and his grandson, Nolan. The family will hold a memorial service in the Bay Area on Saturday, October 10, 2026, at 2 p.m. Those interested in attending should get in touch with Syndonia Bret-Harte, msbretharte [at] alaska [dot] edu (msbretharte[at]alaska[dot]edu), for details and directions.