Marin County has about 750 acres of French broom—a widespread and challenging invasive plant that broadcasts untold numbers of seeds a year—and in the San Geronimo Valley, a volunteer group meets weekly to battle the spread. The members of Broom Service, formerly called the Extractigators, have met nearly every Thursday, weather permitting, for the last five years to pull broom in open space preserves and on private lands, using only their hands and weed wrenches. Led by Woodacre residents Phil Sotter and Mel Wright, the group met at 11 a.m. last Thursday at the Rock Ridge Trailhead; 15 minutes later, they were crouched on a hillside split between open space and private property (invasive plant species don’t abide by property lines, they noted) to pull out any stragglers left from their last visit. They discussed online scams, the new ferry terminal in Richmond and their love of the sound created when a broom root is ripped from the earth. “It’s just the sound of a sheer ecstasy,” Alan Lubow, a Lagunitas resident, said. (One volunteer went so far as to call it “orgasmic.”) To date, they’ve cleared massive areas along Conifer, Willis Evans and Edgewood Trails and on private property off Fern Avenue in Woodacre. They’ve also cleared about a third of the broom in Roy’s Redwoods, and Mr. Sotter added they’re anxious for the county to acquire the golf course “because those two adjacent properties keep seeding each other.” Mr. Sotter explained how he keeps his spirits high in the face of so much of the invasive: “You can’t look at all the broom that lies ahead you. You have to look back and say this is where it isn’t,” he said. The group, comprised of retirees with various backgrounds—a tech marketer, a behavioral science professor and a project scheduler for an engineering firm, to name a few—finishes every workday with a communal lunch. Last week, they were working on property owned by William Binzen, who’s been pulling broom on his lot since the 1980s. “It’s the perfect lighter fuel,” he said. “It burns fast and hot. And the oils crackle.” Mr. Binzen walked over to say hello and was pleased with the muddy bunch. “They embody the genuine spirit of America,” he said. “Phil is a hero; he’s taken it upon himself to do something for his community.” Broom Service meets every Thursday at 11 a.m. Anyone interested in joining is welcome to call the hotline at (415) 488.8888 ext. 350.