A FURTHER CONTRIBUTION TO CLOSED-CONE PINE (OOCARPAE) HISTORY

A new record of a fossil Monterey pine (Pinus radiata D. Don) is recor ded from rocks of the Plio-Pleistocene age, southern California, and t he affinities of other presumed fossil closed-cone pines are revised. This has led to the recognition of two new pine species, Pinus storeya na Axelrod of subsect. Oocarpae and Pinus verdiana Axelrod of subsect. Ponderosae. Geologic evidence indicates that forerunners of the prese nt California and Mexican species of Oocarpae were in proximity in Mex ico during the Miocene. They were isolated following opening of the Gu lf of California, the northward movement of Baja and Alta California o n the San Andreas fault system, and the spread of desert climate. New populations of Pinus radiata developed during the Pliocene (5-2 millio n years) and later as environmental diversity increased. This also ena bled Pinus remorata Mason and P. muricata D. Don, which the fossil rec ord suggests were distinct into the Late Pleistocene, to hybridize in the new topographic-climatic Holocene environments.