BERKELEY – A petite pink flower that hasn't been seen in 70 years has been rediscovered on the flanks of Mount Diablo in Contra Costa County by a University of California, Berkeley, graduate student. The Mount Diablo buckwheat, Eriogonum truncatum, "has been a Holy Grail in the East Bay for several decades," according to UC Berkeley botanist Barbara Ertter, who confirmed the identification in the field on Friday. Last reported in 1936, the flower was presumed extinct, she said, because its habitat has been overrun by introduced grasses. It is one of only three plants, all of them rare,...