Like the scientist she is, Karen Snetselaar is methodically compiling a "before" list, so that "after" the Cynwyd Heritage Trail is built, everyone will know what was there first.
This is knowledge for its own sake, which folks like Snetselaar, head of the biology department at St. Joseph's University, relish and build careers on. But it's useful, too: Her survey of plants growing along the old railroad bed, formerly part of the R6/Cynwyd line, will be shortened from more than 100 to about 20, then offered as a guide to trail visitors for fun and instruction.
"It'll give you an appreciation for how much plant diversity there is here and how much humans impact the natural world," says Snetselaar, who has five students from St. Joe's and Lincoln University helping her with the survey. They hope to finish up this week.
The Cynwyd Heritage Trail is a two-mile-long "rail to trail" project that covers 60 acres from the Cynwyd train station to the Manayunk Bridge. Construction is expected to begin this fall on two paths, one 12 feet wide, straight, and paved; one 8 to 12 feet wide, winding, and made of gravel.
Landscaping already has started, with the planting of 275 trees, including crabapple, serviceberry, river birch, and redbud, but much more is planned.
And although some walkers, runners, birders, and bicyclists are already out there, the new paths, underwritten by $2.4 million from the township, county, and state, are expected to officially open next summer.
"That is our goal," says Christopher Leswing, assistant director of building and planning for Lower Merion Township, which has leased the abandoned railroad corridor for 30 years, for $1, from SEPTA. (SEPTA inherited the old commuter line from the bankrupt Pennsylvania Railroad in 1983.)
Leswing, who says New York's elevated park, known as the High Line, was an inspiration, sees the Cynwyd trail as a "linear park with a garden path," rather than simply a trail. Visitors will be able to veer off to use the ball fields and rest facilities at Cynwyd Park or amble through the woods or embark on a treasure hunt for plants.
Which is where Snetselaar, whose Bala Cynwyd home backs up to the trail, comes in.
One day last week, she and her students were inching along the trail at the base of East Levering Mill Road, between Westminster and West Laurel Hill Cemeteries. Every few feet, they bent down to examine this or that before carefully extracting a sample to preserve in an old-fashioned plant press, to take back to the small St. Joe's herbarium.
The collection will be a reference for volunteers and township employees who manage the trail, serving as a baseline to document future changes in habitat.
Since railroad service stopped in 1985, the area's been badly neglected and abused. Over the last 21/2 years, more than 500 volunteers from the Friends of Cynwyd Heritage Park, the Boy Scouts, St. Joe's, and Bala Cynwyd Middle School have cleared tons of overgrown vegetation and hauled out an encyclopedia's worth of detritus - rusted metal, tires, abandoned cars and shopping carts, fencing, bricks and concrete, and tens of thousands of yards of lawn and garden waste.
Patty Thompson, conservation coordinator with the Lower Merion Conservancy, remembers the old railroad bed as "a corridor of nasties." So nasty, Leswing adds, "we couldn't even go in with machines and clean it up, so much stuff was hiding in the weeds."
With many of the "nasties" carted away, the light shines on what's left, which is mostly weeds.
Butter-and-eggs, for example, which sounds like breakfast but is a pretty European plant whose flowers resemble tiny yellow-orange snapdragons. Linaria vulgaris escaped from North American gardens years ago and now is common in "disturbed" environments, such as roadsides and railroad beds.
Butter-and-eggs has been called every bad name in the plant book - weedy, noxious, invasive. But Snetselaar and her students were captivated. If you don't know better, even if you do, how could you not be?
Same for Queen Anne's lace, dandelion, even plume poppy, which grows 8 feet tall here with pinkish-white flowers. "It's pretty spectacular," Snetselaar says.
Which makes the students wonder.
What, exactly, is a "weed," given that some are quite beautiful? And what does "invasive" mean, given that sometimes even these bad guys feed and shelter wildlife?
Maybe, says Brian Calhoon, a St. Joe's junior from Newark, Del., "a weed is anything you don't want."
"It's undesirable, and not there on purpose," adds Megan Smith of Broomall, another junior.
"It's complicated," says Snetselaar, who specializes in the study of corn smut. (This fungal disease sounds nothing like breakfast, but in Mexico, it's a culinary treat known as cuitlacoche.)
It sure is complicated. Why, even crabgrass seeds feed the birds.
"This is like a good-versus-evil debate," muses Franklin Thelmo, a St. Joe's freshman from Toms River.
Snetselaar has nothing against native plants; she grows many in her own garden. But she believes that the debate over natives, which thrive in their original habitat and provide many benefits for wildlife, versus nonnatives, which arrived from somewhere else by accident or design and aren't as beneficial, must be tempered by reality.
"I think we need to target the really bad invasives and let the rest go," she says. "Don't worry so much about where the plants came from. Aim for diversity."
With a wide range of plants, there's a better chance the area will remain stable, she says.
There are highly aggressive nonnatives that should be yanked, for sure, such as Japanese stiltgrass and mile-a-minute vine. Perhaps others, like giant mullein and oxalis, could be left alone, at least for a while.
"Eventually, they'll get outcompeted by other plants," Snetselaar says.
The group falls silent for a minute before Thelmo, whom everyone calls "Frankie," jumps in with a reality check. "My mom tells me to do stuff and I do it," he says. "She doesn't want dandelions in the yard."
Nor do most people.
"We have an obsession with green lawns and ornate flowers," Smith counters.
Obsessives probably won't care for the Cynwyd trail.
Landscape architect Bryan Hanes has designed a series of meadows along the paths, featuring a broad mix of native wildflowers and grasses. The meadows will take about three years to get established, but by the end of next summer, Hanes says, "there'll be a lot of plants out there."
Pockets of shrubs and more trees, especially behind the residential properties along the trail, will be added over time. There will also be a couple of mowed-lawn areas for throwing a Frisbee and flying a kite, and a no-mow grass mix along the edges of the trail.
"This should keep people out of the meadow and reduce the maintenance required by the township," says Hanes, who hopes to wrap up the landscape design this week and put the project out to bid.
Leswing is working with public gardens in the area to get cuttings for plants that can be grown in the Harriton High School greenhouse for use on the trail. "We want this to be visually stunning, a real model for what you can do in a suburban community," he says.
Snetselaar, for one, is curious to see how that model plays out, how years of abuse by irresponsible humans will segue to a new era of responsible stewardship by others.
Time will tell. Meanwhile, the students are huddled around a plant that "Frankie" suggests "appears to be some kind of garnish for a salad."
"Is it hairy?" Snetselaar asks, prompting a discussion about where the hairs are and how hairy is "hairy." (Good science requires careful observation.)
This nondescript stalk, the budding environmental scientists learn, is hairy willow-herb, or wild chervil, an aggressive nonnative that can grow 6 feet tall. It spreads by underground stems and chokes out all competitors.
"Wow," the students respond, perhaps realizing that this weed is truly a weed.
"Nice name, anyway," Snetselaar says.
Read garden writer Virginia A. Smith's blog at www.philly.com/philly/blogs/gardening
Contact garden writer Virginia A. Smith at 215-854-5720 or email@example.com.