Why has the Japanese knotweed, a plant not native to Western Pennsylvania, invaded the banks of our rivers?

On Monday, more than 70 teens from nine school districts and one home school program will be tested on that and many other environmental issues. They will be competing in the 23rd annual Westmoreland County Envirothon.

Sponsored by the Westmoreland Conservation District, this countywide event focuses on five subject areas: wildlife, forestry, aquatics, soils and an ongoing issue. This year, it's recreation and its impact in the environment, said Tony Quadro, forester and technical program director for the conservation district.

Each participating school will have at least one team of five students. The teams rotate through stations where they will be tested on each subject area.

For example, the Pennsylvania Game Commission supplied educational components for the wildlife station.

Materials are provided by a number of other cooperative agencies, including the Pennsylvania Bureau of Forestry, the Natural Resources Conservation Service, the Westmoreland County Bureau of Parks and Recreation, Carnegie Museum of Natural History's Powdermill Nature Reserve and Penn State Cooperative Extension Westmoreland County.

Students may be asked multiple-choice questions and to identify things such as types of vegetation at the forestry station, animal paw prints at the wildlife station, or fish and salamanders at the aquatics station.

The scores from each station are combined and the teams with the three highest totals will receive trophies. The winning team will go on to state competition May 19 and 20 at Penn State University.

Greensburg Salem's team has been meeting two days each week for the past two months, said their coach, science teacher Angelo Ross.

While any member of a team can answer questions during the event, each Greensburg Salem team member has been concentrating on one of the five subject areas.

"All five are science-oriented [students]," said Mr. Ross.

Participating schools also include Kiski Prep and Burrell, Derry Area, Greensburg Central Catholic, Kiski Area, Mount Pleasant Area, Southmoreland and Yough high schools.

The team to beat may be the Westmoreland Enrichment Class -- home-schooled students from the Norwin area. They won last year's competition and took ninth out of 64 teams at the state competition.

That's where the competition will really get fierce, Mr. Quadro said. The state competition features an oral component in which teams are challenged to deliver a detailed, 12-minute presentation.

Last year's teams were to develop an alternative and renewable energy proposal to "cut consumer energy costs, and significantly expand the alternative fuel, clean energy and conservation sectors," according to the state's Envirothon Web site.

"It's more intense because they're also vying for scholarship money," said Lorelle Steach, Pennsylvania Envirothon project coordinator.

Each member of the state championship team will receive a $1,000 scholarship; second-place finishers will win $500 scholarships; and those on the third-place team will each receive a $300 scholarship.

The state winners will then move on to the Canon Envirothon at Northern Arizona University in Flagstaff from July 20 to Aug. 3.

But for now, it's just good to know that Japanese knotweed is an invasive species, tolerant to a wide range of soils.

"We do want to keep the fun aspect of the competition," Mr. Quadro said.