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Authors of Guide to Santa Ana River Flora to Discuss Findings

New Book Offers Comprehensive Coverage of Santa Ana River Flora

Oscar F. Clarke, former curator of UCR’s herbarium, and coauthors describe 900 plant species

(May 18, 2007)

Cover of <i>Flora of the Santa Ana River and Environs: With References to World Botany</i> (Heyday Books, 2007).

Cover of Flora of the Santa Ana River and Environs: With References to World Botany (Heyday Books, 2007).

RIVERSIDE, Calif. — 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.

The authors of the book will discuss their findings on Tuesday, May 22, from 2 p.m. to 3:30 p.m. and sign copies in the courtyard of Batchelor Hall. Refreshments will be provided. For more information, please call 951-827-3736.

About the authors:
Oscar F. Clarke studied ornithology from renowned birder Wilson Hanna. At UCR, he specialized first in plant pathology and then in nematology. A world-traveler, he has a broad perspective on plant relationships and world flora. Active in the community through many natural history organizations, he mentors students and frequently shares his knowledge with the public.

Danielle Svehla began working with Clarke in 2002. Currently, she is studying plant community ecology in the Energy and Resources Group at UC Berkeley.

Greg Ballmer is a research associate in the Department of Entomology at UCR, specializing in larval host plants of local butterflies, moths, and other insects. He has a strong affinity for the Santa Ana River and its riparian communities.

Arlee Montalvo is a plant population biologist and restoration ecologist who has studied reproductive biology and variation of wild plants. She also focuses on the natural history and variation of Southern California’s plants. She works for the Resource Conservation District in Riverside, Calif.
Thousands of images, such as that of <i>Opuntia Basilaris</i> (Beavertail Cactus) seen above, are included in the book.

Thousands of images, such as that of Opuntia Basilaris (Beavertail Cactus) seen above, are included in the book.



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 has exceeded 21,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of more than $1 billion.

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