Sir John Rupert Hunt Thouron, 99, of Unionville, a horticulturist who established a British-American student exchange scholarship, died Feb. 6 at his winter home in Hobe Sound, Fla.

Sir John was knighted by Queen Elizabeth II in 1976 in recognition of the Anglo-American educational exchange program he and his wife, Esther duPont Thouron, launched in 1960.

The Thouron University of Pennsylvania Fund for British-American Exchange has sponsored post-graduate studies at Penn or at British universities for more than 700 students.

Sir John was born to an American father and a British mother in Cookham, England. During World War II, he was an officer with the Black Watch, an infantry battalion of the Royal Regiment of Scotland. His experience watching British and American troops fight side by side inspired him to establish the British-American Exchange.

He and his wife married in 1953 and moved to Unionville, where she rode horses and he created an English-style estate, Doe Run. He transformed open fields into sculpted stretches of lawn set off by borders of massed plantings, rose gardens, pastures of wildflowers, a brookside Alpine garden, and a cottage garden. He grew flowering myrtle shrubs that were cultivated from a sprig taken from the wedding bouquet of Queen Victoria - his grandmother was an attendant.

Sir John often opened his gardens for fund-raising events, including those benefitting the Chester County SPCA.

He regularly won ribbons for his plant entries at the Philadelphia Flower Show. In 1980 his donation of a rare yellow clivia to the Delaware Center for Horticulture launched the center's annual rare plant auction. Sir John was a member of the Bidermann Golf Club in Wilmington, where he scored 75 at the age of 88.

He is survived by his grandchildren, J. Rupert Thouron and Rachel Nicoll, and two great-grandchildren. Esther duPont Thouron died in 1984. His son John J. "Tiger" Thouron died in 2006. Sir John was also predeceased by his former wife, Lorna Elliot Thouron.

The funeral and burial were private.