REDMOND − The small, white flower clusters can reach up to 10 feet and, to the unaware landscaper, would look pretty in a garden. Its leaves are bright green and the root looks like a carrot or parsnip. But the plant is also an invader that can wreak havoc if it’s not contained.

The clusters are poison hemlock, a noxious weed that, as its name suggests, is toxic to people and animals. It’s one of dozens of harmful plants on King County’s list of noxious weeds − nonnative plants that often grow rapidly and can hurt the ecosystem by overwhelming native plants − that officials want to control, often using field reports from the public.

A new mobile app called King County Connect, which launched Tuesday, aims to make the process easier for residents who want to report noxious weeds to specialists. The app allows users to take a photograph of the plant, submit the photo with an automatic date and location and receive status updates to find out what county employees did in response to the tip.

Users can match their photo using a photo library of common noxious weeds and include the GPS coordinates of the plant. It’s a far cry from the previous system, when residents had to call or submit a written report, often with descriptions like “on the side of the road,” or “in the park” said Sasha Shaw of King County’s Noxious Weed Control Program. At a news conference Tuesday at Marymoor Park, Shaw and other county specialists demonstrated how to use the app using noxious weeds sitting on a table.

“In the past, someone called, said ‘there’s a plant, it’s green, it has flowers,’ ” said Shaw, who is an expert in noxious weeds. “This app will help find them more successfully.”

The location will be automatically uploaded to the noxious weed program’s map, allowing the specialists to identify large spreads of weeds and areas where they might be particularly harmful, such as near a school or park. They’ll prioritize toxic weeds like poison hemlock or tansy ragwort, a plant best known for poisoning horses, for removal.


The app originated at a hack-a-thon last year among King County IT employees and representatives from Microsoft and Slalom, a Seattle consulting company. Noting that the county’s noxious-weed website was heavily visited, the employees wanted to create a better tool for users, said Gretchen Peri, of Slalom. 

Many cities have smartphone apps for residents — Seattle has the “Find It, Fix It” app to report issues like abandoned cars or graffiti. But the noxious-weed app is unique in letting users connect with experts directly, Peri added.

King County Executive Dow Constantine called the app a way for residents to be armed and ready as “soldiers in the battle against noxious weeds.” Over the two-decades-long battle, county officials have detected nearly 18,000 infestations of about 50 species that cover a total of 1,460 acres.

About half have been eradicated, but seed reproduction makes clearing and eradication difficult. The poison hemlock plant, for example, produces up to 40,000 seeds.

“Weeds have their ways of getting around,” Shaw said.

Along with the new app, residents can also report noxious weeds to the control program website, by email at or by calling 206-477-9333.