Oscar Clarke, a self-taught botanist, author and founder of The Herbarium at UC Riverside, died Saturday. He was 93

Mr. Clarke’s friends and colleagues described him as a “walking encyclopedia of local natural history,” said his friend, Elizabeth J. Lawlor, in an email. He started the university’s herbarium in 1966 and was its curator until 1979.

After his retirement, Mr. Clarke traipsed  along Inland waterways, collecting specimens to document in his 2007 book, “The Flora of the Santa Ana River and Environs.”

Even as late as February, Mr. Clarke still occasionally volunteered at the herbarium, a resource for researchers, farmers and private biological consulting firms, Lawlor said. “Oscar was known as a larger-than-life character and a mentor to many botanists and ethnobotanists,” she said.

Mr. Clarke also was active in education and conservation groups, including the California Native Plant Society, Audubon Society, Sierra Club and Tri-County Conservation League.

” Mr. Clarke was born in Colton in 1919 and grew up collecting bird eggs for ornithologist Wilson Hanna. In 1941, he began work at UCR when it was known as the Citrus Experiment Station. After a stint in the Army during World War II, he returned to the Citrus Experiment Station and worked in nematology and plant pathology before starting the herbarium.

“Oscar was an amazing natural historian and enthusiastic teacher. He was brimming with ideas and information and was very generous with his time. He touched our hearts and our minds,” said Arlee Montalvo, Mr. Clarke’s co-author and a plant restoration ecologist at the Riverside-Corona Resource Conservation District.

Mr. Clarke had been diagnosed with prostate cancer and was in hospice care at home for the last month, she said.

He is survived by his wife, Marsia Alexander-Clarke, and children Taffy, Ken and Diane and their families.

A memorial for Mr. Clarke will be held at 3 p.m. Sunday, March 17, at the UCR Botanic Gardens off Big Springs Road and North Campus Drive.

In lieu of flowers, Mr. Clarke’s family asked that donations to be directed to The Herbarium at UCR, in care of professor Giles Waines, UCR Department of Botany and Plant Sciences, 900 University Ave., Riverside, CA 92512.