Crossosoma 34(2), Fall-Winter 2008 
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technician in the Plant Pathology Department. Beginning in the late 1940s, 
he worked under Dr. Richard Baines (1905-1979), researching parasitic 
nematodes that damaged regional citrus production. He discovered a new 
nematode, Haplolaimus clarkeae , named in his honor. He also became known 
as the Experiment Station’s unofficial botanist, routinely answering the public’s 
questions about plants. During this period he guided Dr. Carl Epling of UCLA, 
the expert on taxonomy of the mint family, to sites on the Experiment Station 
grounds where Salvia apiana and S. mellifera hybrids were found. Also about this 
time he published his first paper - on the identification of Amaranthus (pigweed) 
in southern California orchards. In 1966 Professor Frank C. Vasek selected Oscar 
to manage and improve the small Biology Department herbarium. Dr. Vasek had 
begun the herbarium in about 1956, shortly after his arrival at UCR, but it was 
staffed only part time by students. Oscar lacked a university education but was 
the recognized expert in the local flora and thus became the herbarium’s first 
paid curator. Dr. Vasek himself is best known for his work on Clarkia evolution, 
juniper taxonomy, and the discovery of the ancient creosote rings of the Mojave 
Desert. 
As the herbarium curator, Oscar first began to think of himself as a professional 
botanist. He became an expert on agricultural weeds; he gave public lectures and 
classes on horticulture and wild edible plants; and collected specimens for the 
herbarium and for botany courses. He curated the herbarium from 1966-1979, 
when he retired. He increased the size of the UCR Herbarium by some 10,000 
specimens from all over the world but especially from southern California. In 
the 1970s he was a familiar figure around the UCR campus and especially the 
Biology Department, where he often was seen running, carrying bundled plant 
material for botany classes. In the late 1960s and through the 1970s he led or 
participated in several botanical trips to Mexico, beginning in 1967 with a trip to 
Chiapas, accompanying Earl Lathrop, Professor of Plant Ecology at Loma Linda 
University and Robert Thome of Rancho Santa Ana Botanical Garden. Oscar 
collected over 850 specimens in Mexico under his own name, and assisted others 
(e.g., Thome, A. Sanders, A. Gomez-Pompa, and others) with the collection of 
many more. He has had a long interest in both weeds and cultivated plants and has 
made specimens of nearly a thousand plants in each category. 
Among Oscar’s important collections was the first, and still only, specimen of 
Helianthella durangensis Turner, a plant he found in the mountains of Durango, 
Mexico in 1969. On the same trip he rediscovered Trichocoryne connata, a 
species that had not been seen since it was described from an unknown locality 
somewhere in the state of Durango in the late 1800s. 
