A wildfire threatening one of the world's greatest collections of giant sequoias has more than doubled in size in the past 24 hours, growing to nearly 1,600 acres with further growth expected in the coming days.

There stands in the dry and rugged canyon in the backcountry of Big Bend National Park in West Texas a worn and diseased oak tree from a species once thought to be extinct but which now offers hope that it can help revive the species last spotted more than a decade ago.

Yosemite National Park's famous Mariposa Grove of Giant Sequoias was threatened Saturday by a growing wildfire that led to the evacuation of not just the grove but the nearby Wawona area. While more than 200 firefighters were trying to tackle the 703-acre Washburn fire, weather conditions were not helpful, as the forecast called for growing temperatures and reduced humidity through the weekend.

Significant amounts of downed timber and mixed timber forest were fueling a wildfire Friday near the Mariposa Grove of Giant Sequoias in Yosemite National Park, where ground crews and aircraft were trying to slow the blaze.