John Kingsbury, professor emeritus of botany, who built a small island in the Gulf of Maine into an immersive, summerlong living classroom for students eager to learn about the land and the sea, died May 27 in Norwich, Vermont. He was 94.

Kingsbury’s vision for Appledore Island, Maine, allowed undergraduate students studying marine science to become hands-on researchers at the Shoals Marine Laboratory – a seasonal field-station collaboration between Cornell and the University of New Hampshire.

Fifty years later, students still spend their summer at Shoals Marine Laboratory and alumni still participate in learning vacations, conducting studies on the island and on the lab’s research vessel, the John M. Kingsbury – his namesake.

“Appledore Island is a magic place,” Kingsbury said in his 1991 book “Here’s How We’ll Do It,” an informal history of the Shoals Marine Laboratory. “Even the casual day visitor senses it. Appledore Island displays the natural world as it is, sometimes raw, sometimes exquisite, always absorbing.”

On campus, Kingsbury taught courses on algae in the College of Agriculture and Life Sciences, and wrote the textbook, “Poisonous Plants of the United States and Canada,” specifically to train doctors and veterinarians. He spent eight years gathering material for it, crossing North America twice.

Kingsbury acquired and oversaw a poisonous plant garden once adjoining the College of Veterinary Medicine and taught the veterinary students about those plants. The garden is now located at the Cornell Weed Science Teaching Garden adjacent to the Walter C. Muenscher building, named for the noted botanist, a mentor.

Kingsbury’s book “Deadly Harvest,” completed in 1965 and illustrated by noted artist/illustrator Elfriede Abbe, with drawings by his wife, Louise Kingsbury ’57, discusses the history of plant poisoning in humans and animals. It is replete with factual data, as well as stories of medieval methods of deliberate poisoning and accidents.

Kingsbury’s other books include “Seaweeds of Cape Cod and the Islands,” “200 Conspicuous, Unusual, or Economically Important Tropical Plants of the Caribbean,” and “The Rocky Shore,” an illustrated account the rock-strewn coast of New England.

In 1997, when a 60-pound pumpkin mysteriously appeared at the spire atop the 173-foot-tall McGraw Tower soon before Halloween, Kingsbury – by then an emeritus professor – was pressed back into service for his botanical expertise.

The pumpkin remained there through Ithaca’s brutal winter and many wondered if it was real.

To determine the pumpkin’s authenticity, Provost Don M. Randel offered a serious academic prize – the cost of textbooks for a semester – to the students who could biologically affirm the pumpkin. Appointed by Randel, Kingsbury led a commission to judge the contest results.

Many students, alumni, faculty, staff and media – enamored by the pumpkin fever on campus – waited for the verdict. After gathering data in April 1998 from the students’ microscopic sample slides, videotapes and photographs, the Kingsbury Commission offered a four-word executive summary: “It is a pumpkin!”

John Merriam “Jack” Kingsbury was born on July 4, 1928 in Boston to Willis and Constance Kingsbury. He earned his bachelor’s degree in 1950 from the University of Massachusetts, and his master’s (1952) and doctorate (1954) from Harvard University.

Kingsbury served as an instructor at Brandeis University from 1953-54, then joined the Cornell faculty in 1954 as an assistant professor. At Cornell, he served as an associate professor, a professor and became emeritus in 1983.

He conceived of a living laboratory on Appledore Island in the 1960s, navigating fundraising, a gauntlet of approvals at Cornell and the local building laws. The trustees approved the project in July 1968.

The isle facility formally opened in 1973 and was dedicated in 1975.

The summer program was originally designed to acquaint students with marine sciences ranging from invertebrate zoology to the economics of coastal zone management. The program accentuated fieldwork, natural habitats and ecological interconnections.

It also served good food. Kingsbury brought along a chef – whom he’d hired from the Ithaca Yacht Club – to feed the hard-working undergraduates. Their menu included fresh mussels and chanterelle mushrooms gratineed with cream, lobster with juniper berries, and chocolate mousse baked Alaska.

“Morale on an isolated island varies directly with what happens in the kitchen,” Kingsbury said, in a Cornell press release touting news about the lab. “Students will put up with ants in their beds, plaster in their faces, dirty clothes, wet sneakers, one shower a week and fussy safety regulations if they are happy in the dining room.”

The young laboratory faced a crisis in autumn 1973, when shipping magnate Aristotle Onassis and his Olympic Refineries sought to build an oil refinery onshore in nearby Durham, New Hampshire, with a pipeline extending to a supertanker terminal adjacent to Appledore Island, which sits in Maine but borders New Hampshire.

The New Englanders – along with Kingsbury – rapidly banded together to oppose and thwart the proposed refinery. Worried that it would ruin the pristine natural area, the professor told the New York Times in January 1974 that an oil dock “will, quite simply, put us out of business.”

Later that spring, the Durham town board handily voted down the proposal.

Kingsbury also reconstructed the 19th century poet Celia Thaxter’s serene garden on Appledore Island. To this day, the Shoals Marine Laboratory allows island visitors to take a day trip to tour it.

In addition to his academic work, he served as director of Cornell Botanic Gardens in 1981-82. He was a U.S. Fulbright Senior Scholar in Australia, a National Science Foundation faculty fellow and a fellow at the American Academy of Veterinary and Comparative Toxicology.

Kingsbury is survived by his wife, Louise; his daughter Joanna Merriam Kingsbury Smith ’83 and her husband David Smith; and granddaughters Celia Smith Luterbacher ‘09, M.P.A. ’11 and her husband Jeremy Lutenbacher, Ph.D. ‘12 ; and Molly Smith Dunn ’12 and her husband Stephen Dunn; and great-grandson Ezra Luterbacher.