Oscar F. Clarke, a natural historian who established UC Riverside's herbarium, has published with three other researchers a comprehensive seminal guide to the flora of California's Santa Ana River.

Flora of the Santa Ana River and Environs: With References to World Botany (Heyday Books, 2007) describes 900 plant species, accompanied by 3,200 images and illustrations, and serves as an introduction to basic botanical concepts.

"We have arranged the book by evolutionary relationships to aid readers in plant identification," said Clarke, whose coauthors are Danielle Svehla, Greg Ballmer and Arlee Montalvo (author biographies are included below). "Our book also presents historical and cultural uses of the flora of the Santa Ana River; the associations of both native and introduced plant species with insects, birds, and mammals; and plant diseases."

The Santa Ana River is the largest watercourse in the heavily populated coastal plain of Southern California. The river and its environs are home to nearly 1,400 plant species.

In their research, Clarke and his team recorded and photographed several new plants, including a rare plant - Phacelia stellaris (Brand's phacelia) - that had been considered extinct. They examined 1365 plant species in total along the Santa Ana River and its tributaries. The researchers confined their research to flora below 3,000-foot elevation.

Clarke worked for UCR's Citrus Experiment Station before the founding of the UCR campus. In 1966, he established UCR's herbarium, working there as its curator until his retirement in 1979. He has studied and taught natural history throughout his life.

Clarke and Montalvo will give a presentation on the book at 3 p.m., April 21, on the second floor of the Riverside Public Library, 3581 Mission Inn Avenue, Riverside, Calif. The 90-minute presentation will include time for questions, discussion, book sales and signing. Refreshments will be provided.

The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world.
Reflecting California's diverse culture, UCR's enrollment of about 17,000 is projected to grow to 21,000 students by 2010. The campus is proposing a medical school and already has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. With an annual statewide economic impact of nearly $1 billion, UCR is actively shaping the region's future.