The varieties of plants, shrubs and trees carpeting Skyline Wilderness Park and Napa County’s open spaces are numerous – but not all are welcome.

On Sunday, the hilly preserve east of Napa became an open-air classroom for more than 40 local volunteers. Through a combination of lectures, presentations and a hike – along with a smartphone app that helps track plant images and data – they received a course in strategizing and carrying out campaigns to keep in check the numerous plant species, brought in from other states and countries, that can rapidly roll back the North Bay’s homegrown flora if left unchecked.

Sunday’s program was the first of eight scheduled over the next two months across the Bay Area by the California Invasive Plant Council, which maintains a statewide inventory of non-native species and their various threats to ecosystems. Among those attending were volunteers with the Land Trust of Napa County, the county Resource Conservation District, Master Gardeners and others, according to organizer Alene Spindel of the council.

The common foe of volunteers and teachers is the introduction of plants into habitats lacking the flora and fauna that would shade them, compete for soil and water, or eat them in their native territories. Without such controls, such species can swiftly take over a locale – pushing out not only the incumbent plants but also other plants or animals dependent on them for food, shade or shelter.

“Prevention is probably the least sexy approach but it delivers the most bang for your buck, and it’s something where volunteers are critically important, with their many eyes and ears,” said Michael Gordon of the Napa County Flood Control and Water Conservation District.

Speakers at the Napa program laid out principles stretching far beyond the physical pulling and tilling of noxious greenery – from preventing invasive seeds from hitchhiking on vehicles and clothing, to surveying parklands to detect invasive plants early, to researching local ecosystems to prioritize what plants most need immediate protection.

Seeing such details laid out can encourage others to take on even difficult-seeming restoration tasks, according to Chino Yip, outreach coordinator for the Napa County Regional Park and Open Space District, one of those taking part in the program at Skyline Park.

Pointing to the district’s work at Westwood Hills Park attacking the spread of French broom – whose stems can grow 20 feet high – the problem is the seeds can be in the ground 10 or 20 years,” he said. Nonetheless, “it’s an amazing difference (now) – you used to see it on the hillsides near the parking lot.” Volunteers have spent some 10,000 person-hours removing the plant from Westwood Hills, not only giving native plants a better chance but creating open-sun areas that also slow the growth of poison oak, Yip estimated.

By early afternoon, the classroom session gave way to an uphill stroll to put one part of the plan into action.

On an hour-long hike up the rain-soaked Lake Marie Road trail, volunteers toted not sickles and shears but their cellphones. At various points they stopped, pointed their phone cameras toward certain plans and snapped away – then captured the pictures, locations and surroundings with Calflora Observer Pro, an app that recorded the images, GPS coordinates and notes to be shared with a statewide registry of greenery, native and non-native.

While not as greedy and dominating as kudzu or French broom, interlopers were not difficult to spot; in quick session the hikers’ phones turned toward samples of vetch, milk thistle and finally a thorny branch of Himalayan blackberry, which Chip Bouril held up for his companions to view.

“The Himalayan blackberry will make more and better fruit than the native blackberry,” said Bouril, a soil conservationist with the Resource Conservation District, before adding wryly: “That doesn’t make it a better plant.”

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A photo caption has been modified since the original posting to correctly identify a bay laurel, a tree species native to California.


City of Napa/Town of Yountville Reporter

Howard Yune covers the city of Napa and the town of Yountville. He has been a reporter and photographer for the Register since 2011, and previously wrote for the Marysville Appeal-Democrat, Anaheim Bulletin and Coos Bay (Oregon) World.