John Ormsbee Simonds, a pioneering modernist landscape architect and one of the most prominent and influential of his generation, died of natural causes Thursday at his home in Ben Avon Heights. He was 92.

Mr. Simonds, co-founder of Simonds and Simonds in 1940, designed the Chicago Botanic Garden in the 1960s, using the natural wetlands to create a series of linked lagoons where there are now more than 25 themed gardens.

Also an urban planner, Mr. Simonds designed four new towns, including Miami Lakes and Pelican Bay in Florida, and was the planner of record for more than 80 planned communities.

In Pittsburgh, he designed two Downtown public plazas -- Mellon Square and Equitable Plaza -- and many playgrounds and parklets, including Marmaduke, Kennard and Swisshelm Park. In 1966, the firm revived Lake Elizabeth with a contemporary renovation of Allegheny Commons Park on the North Side.

Born in the prairie town of Jamestown, N.D., he was the son of a circuit-riding minister.

"Our home had the only tree in Jamestown. Every Sunday all the people of Jamestown would stand under it and tell lies," Mr. Simonds recalled with a quiet laugh in a 2002 interview at his home, which he designed around 1950 with the help of his friend and frequent collaborator, the late architect Dahlen Ritchey.

Mr. Simonds was 7 when his father became pastor of the First Presbyterian Church in Lansing, Mich.; the family later moved to Niles, Mich. Mr. Simonds studied landscape architecture at Michigan State University, but at the end of his junior year, he went off by himself to see the world.

"In the Orient, I got really excited about landscape architecture. Michigan State and Harvard were all [dominated by] Beaux Arts [theory] and every plan looked like a little Renaissance garden with cross-axes and fountains in the middle. And if you didn't have that, you didn't pass," Simonds recalled. "In Japan, everything was asymmetrical and fitted into the landscape."

Studying on scholarship at Harvard's Graduate School of Design, Mr. Simonds found refuge from the hidebound classicism of the landscape architecture department under the wings of proto-modern architects Walter Gropius and Marcel Breuer, graduating in 1939.

In 1963, he wrote "Landscape Architecture," a widely used college textbook that has sold more than 100,000 copies. Its fourth edition is now in production. Mr. Simonds was on the faculty of Carnegie Mellon University for 13 years and a visiting lecturer at many schools in the United States and abroad.

He also was the author of "Virginia's Common Wealth," a statewide environmental action plan commissioned by the Virginia General Assembly and still in use today.

A past president and fellow of the American Society of Landscape Architects, Mr. Simonds was awarded the group's highest honor, the ASLA Medal, in 1973. In 1999, he received the ASLA's President's Centennial Medal, awarded for the first time "for unparalleled contributions to landscape architecture and service to the ASLA in the 20th century."

He also was a fellow of the Royal Academy of Design in Great Britain.

In 1970, Simonds and Simonds, the firm he founded with his brother Phil in a loft in Ben Avon Heights and later moved to Ross Street, Downtown, became Environmental Planning and Design. Mr. Simonds worked there until 1983, and thereafter continued as emeritus.

Mr. Simonds is survived by his wife, Marjorie, whom he married in 1943, as well as four children and seven grandchildren. There will be no funeral service or visitation; a memorial service will be announced at a later date.