Botanists’ ‘holy grail’ blooms near Antioch

Mount Diablo Buckwheat Mount Diablo Buckwheat Photo: Heath Bartosh Photo: Heath Bartosh Image 1 of / 10 Caption Close Botanists’ ‘holy grail’ blooms near Antioch 1 / 10 Back to Gallery

A jolt of adrenaline is coursing through the normally placid botany community in the East Bay after the discovery of a prodigious patch of extremely rare wildflowers that, until a few years ago, were thought to be extinct.

The half-acre cluster of critically endangered Mount Diablo buckwheat was spotted at the 6,096-acre Black Diamond Mines Regional Preserve, near Antioch, by two botanists who saw a pink hue of growth on rolling hills that normally would be covered with California’s signature golden grasslands.

The finding came in May, but was announced Wednesday after months of secrecy usually reserved for matters of national security. East Bay Regional Park District officials declined to show The Chronicle exactly where the flower had been found out of fear that its location would be revealed, thus prompting hikers or vandals to flock there.

The plant with the cotton-candy-like flower had first been rediscovered in 2005, in minuscule amounts, in a remote area of Mount Diablo State Park after a 69-year absence from the biological record. The discovery of a second, much larger cluster, was likened by giddy scientists to seeing a unicorn a second time.

“It’s a really exciting discovery because the previous place where they found this plant was a small location, and the biggest number of plants there on any given year was 100,” said Michele Hammond, botanist for the park district, which manages Black Diamond Mines. “This is almost 2 million plants. We’re super excited about it.

“That being said,” she added, “having this plant in only two locations in the world is not ideal.”

It was Heath Bartosh and Brian Peterson, of Martinez-based Nomad Ecology, who spotted the bright pink buckwheat blossoms after being hired by the park district to do a survey of rare plants at Black Diamond Mines. The two men could hardly believe their eyes when they stumbled upon an estimated 1.8 million specimens of the powder-puff plants with their distinctive wishbone-shaped stems.

“I had personally hoped to find this thing for so many years, and then I suddenly walk up to this population that was so numerous,” Bartosh said Wednesday. “It was like, wait a minute, this can’t be real. I’m dreaming.”

Mount Diablo buckwheat, known scientifically as Eriogonum truncatum, was first recorded in 1862 on the Mexican rancho known as Los Meganos on the edge of Brentwood, which at that time was owned by John Marsh, one of the first American settlers in the area. The plant was documented in only seven locations over the next 78 years —the last time in 1936 by Mary Bowerman, who later cofounded the conservation group Save Mount Diablo.

Bowerman cherished the plant and, near the end of her life, often asked people whether any new specimens had been found. It was presumed extinct until 2005 when Michael Park, a 35-year-old UC Berkeley graduate student studying plant life on Mount Diablo, found about 20 of the flowers surrounded by chaparral. The finding was touted internationally as a botanist’s “holy grail.”

Bowerman learned about the discovery just before her death, Bartosh said. He said the new population was found about a mile from Marsh’s Ranch, remnants of which still exist, and might very well be the site of a previous sighting in 1886.

Mount Diablo buckwheat, an annual plant that blooms in the spring and summer, is one of 29 plant species on Mount Diablo considered rare or endangered. Eleven are endemic to the region.

While experts believe incursions by nonnative plants and development are responsible for the wildflower’s near-demise, it is so rare that botanists have had very little concrete information about it. Some thought it grew only in chaparral country, but the new patch spread across a dry grassland in “highly erosive soils,” Bartosh said.

After the 2005 find, a working group of federal, state and local scientists formed to try to spur the plant’s recovery. They collected seeds, set up cameras to monitor the buckwheat, and propagated the species at UC Berkeley’s Botanical Garden, all while trying to make it flourish on Mount Diablo. But the effort has been difficult.

At one reintroduction site on Mount Diablo, officials said, the group sowed 80,000 seeds. But experimental plantings never yielded more than 200 small plants. The same challenge now will be taken up with the Black Diamond Mines flowers.

“The Antioch population is a great discovery. Its habitat is quite different from the 2005 rediscovery site, and provides valuable information for efforts to develop new populations,” said Holly Forbes, curator and conservation officer at the UC Botanical Garden.

“The new population is giving us more hope than we’ve ever had for the future of this species,” said Cyndy Shafer, a senior environmental scientist for California State Parks. She said it was lucky that both discoveries happened on public land, “demonstrating the immense importance of protected lands in preserving biological diversity.”

One major concern, though, is that the two distinct patches are on steep slopes vulnerable to fire and landslides. Still, researchers hope the new cluster yields secrets that will help them determine how to reintroduce the species.

Hammond said the discovery is more than just a bunch of pretty flowers in a field.

“This is the ultimate discovery in a rare plant treasure hunt,” she said. “I love seeing the crazy diversity of flowers in California. If we don’t protect them, one by one these species are going to drop out and we will lose the fun of walking through an area and seeing different flowers.”

Peter Fimrite is a San Francisco Chronicle staff writer. Email: pfimrite@sfchronicle.com Twitter: @pfimrite