HUMBOLDT COUNTY — Standing next to Lt. Gov. Gavin Newsom on a hill overlooking southern Humboldt County, a second-generation cannabis farmer pointed to the valley below. “There’s one,” he said, gesturing at a clearing in the trees. “And there. And over there. They’re all over.”

Newsom and Rep. Jared Huffman, D-San Rafael, nodded as they gazed at marijuana grow operations below, taking it all in. They were in the middle of what had been billed a “Cannabis Fact Finding Tour” — a new rite of passage for California politicians grappling with questions of legalization.

It was a journey to the state’s Emerald Triangle, three northern counties that produce 60 percent of the weed consumed in the United States, and where calling the local herb “marijuana” is offensive to some for its perceived negative connotation. Here, the scientific term “cannabis” is preferred, and fear of law enforcement still runs high. Though they were the guests of honor, Newsom, Huffman and Assemblyman Jim Wood, D-Healdsburg, were escorted to this 450-plant farm without learning its address or the grower’s full name.

Yet, the fact that top officials even made the trek is a sign of how California’s 50,000-plus cannabis farmers are already becoming a political force. Growers are shaping potential 2016 ballot measures to legalize recreational use of marijuana and influencing legislation in Sacramento that would regulate the state’s 19-year-old medicinal market in unprecedented ways.

“We are at a historic moment here, and people know change is coming,” said farmer Luke Bruner, founder of California Cannabis Voice Humboldt and the business manager of Wonderland Nursery in Humboldt. “The best cannabis on planet Earth comes from Humboldt County. But all these people are trying to write laws about us without us. We’re not going to be kept out of it.”

Growers largely stayed out of California’s last legalization fight in 2010, when voters in Humboldt, Mendocino and Trinity were among the 47 counties that opposed Proposition 19. Only 11 largely urban counties supported it.

Back then, growers were suspicious of legalization, in part because they weren’t consulted in crafting the ballot measure. Now, with mainstream attitudes toward cannabis softening and recreational use legal in four states, growers see legalization as inevitable — and remaining underground a risk.

Fear corporate takeover

California growers want to come out of the shadows politically because they’re worried that major corporations — be it Big Tobacco or Big Pharma — will buy land in the Central Valley should legalization occur. They fear massive farms would crank out, as one farmer put it, “the Two-Buck Chuck” of cannabis — an inferior but cheaper product that could cut deeply into their business.

Newsom grasps this concern. Corporate interests would rewrite the state’s rules “and they will try to write you out,” Newsom told a crowd of 200 at a public forum in Garberville during his late May trip. “We cannot let that happen.”

The audience gave him a standing ovation.

Hezekiah Allen, a third-generation cannabis farmer, was inspired to get involved politically the night he watched the Prop. 19 results roll in five years ago.

“I remember sitting on the farm, it was the middle of harvest season, 20 trimmers working, and we were thinking, ‘Wow, what would happen if this passed?’” said Allen, now the executive director of the Emerald Growers Association.

Many shared Allen’s concerns, but few would speak out publicly after living off the grid for so many years. California’s medical marijuana law allows people to grow and sell cannabis to dispensaries for patients with a medical diagnosis. But federal law still considers marijuana an illegal drug on the same level as heroin, one that has “no currently accepted medical use.”

They fear transporting their product to market because the pot laws vary between neighboring jurisdictions. They are wary of approaching the local farm bureau for help. Banks don’t want to deal with them, and few even try to open accounts, fearing the feds could confiscate funds. “So everybody’s got a tree hollow or a hole or something,” Bruner said.

They are reluctant to tell people what they do. As one farmer said, “there’s a lot of people who are ‘carpenters’ up here.”

Shortly after he helped to reboot the Growers Association about six months ago, Allen surveyed thousands of farmers. One survey question asked: “Can I use your name as a farmer?” Only about 150 volunteered a name.

“In our community, it has always been that the lower the profile you keep, the more successful you’d be,” Allen said.

Growers demonstrate

But that has been changing over the past several months. A few weeks ago, 150 farmers, many wearing “I am a farmer” shirts, demonstrated in Sacramento.

Allen said farmers are focusing on four legislative priorities in Sacramento. They want:

•Cannabis to be regulated through the California Department of Food and Agriculture, so it can be openly and legitimately studied by scientists, academics and researchers.

•A business licensing program to ensure smaller growers can continue to compete in a legal market.

•Increased environmental regulation that would benefit farmers who are not illegally tapping into water supplies.

•An appellation system similar to the wine industry.

“You legally can’t market wine called Napa unless it was produced in Napa,” Allen said. “We’d like to see the same for cannabis from Humboldt.”

Allen said the good news for farmers is that most of the legislation moving through Sacramento includes these policy priorities to varying degrees.

Attitudes are changing so much that Board of Equalization member George Runner, a Republican who opposes recreational legalization, took a similar fact-finding tour in Humboldt a few weeks ago with liberal San Francisco board member Fiona Ma.

“We’ve got to figure out how to successfully regulate it for the purposes of taxation,” Runner said.

The most recent estimate is that dispensary sales range from $700 million to $1.3 billion, resulting in $59 million to $109 million in sales tax revenues annually. So little is known about the industry, the board last month launched a study of its scope with the goal of increasing tax compliance.

Bruner welcomed it.

“People want to do the right thing, they want to pay their taxes,” Bruner said. “They don’t know how.”

Though legalizing marijuana would be a boon for tax collectors, nobody really knows how big the industry already is.

Newsom’s eyes widened as he walked through a nursery filled with starter plants. Cannabis cultivators told him the number of plants nurtured there annually wouldn’t equal 1 percent of the 40 million plants growing in the Emerald Triangle — which is roughly the size of West Virginia.

Newsom surprised

“Every time I think I’ve wrapped my head around this issue, I realize how much there is still to learn,” said the former San Francisco mayor, who was invited on the trip because he heads a state commission exploring issues raised by legalization.

At the Garberville public forum, Newsom, who supports legalization, was greeted as a hero just for showing up.

“I’m having a Barack Obama moment,” a silver-haired man in the audience told Newsom.

“I never expected an African American president. And I never expected the lieutenant governor of the state to be up here talking about these issues.”

Want to protect rights

Many there were growers who want to see their current way of life protected, as Beth Allen put it. She’s been growing for 41 years, mostly in Humboldt, and the money she earned helped her build a restaurant and put her kids through school.

“I’m worried that things will change a lot if this isn’t written the right way,” Allen said. “So much of the community here depends on this. We’ve got to do it right.”

Joe Garofoli is a San Francisco Chronicle staff writer. E-mail: jgarofoli@sfchronicle.com Twitter: @joegarofoli