Despite forecasts of rain, nine hearty individuals clad in Windbreakers and hiking boots congregate in the parking lot of Carderock Recreational Area in Great Falls Park, Md., early on a Sunday afternoon.
The group includes a lobbyist, a college senior, a commercial-construction estimator, a proposal manager for Boeing Co., and an environmental scientist. They wait expectantly at the open tailgate of a station wagon to receive magnifying lenses and copies of "Newcomb's Wildflower Guide" from Stephanie Mason, senior naturalist at the National Audubon Society.
"It's a really big plant world," she says. "In Maryland alone, there are over 2,200 species of herbaceous plants. Sometimes people get frustrated - that's why you have 'keys.' "
Keys are the characteristics of a plant that unlock the secret to its identity. They are the components of what Ms. Mason calls a plant's "composite picture." They help people make sense of the teeming flora that surround them. They are just some of many tools people acquire when they enroll in courses, lectures, or nature walks offered by museums of natural history, botanical gardens, arboretums, horticultural departments of community colleges, local nature centers, branches of the Audubon Society, or commercial nurseries.
The content ranges from introductory classes on ecology to plant identification, from instructions on landscaping or pruning to garden photography or ikebana flower arrangements.
Broad-based curricula tend to encompass the wildlife and insects that make up the local ecosystem and often involve field trips or laboratory work where students examine specimens, identify plants, and learn about pollination and seed dissemination.
Mary Metler has garnered useful information in evening horticultural classes at Prince Georges County Community College in Largo, Md. Although she has worked for two years at Behnke's nursery in Beltsville, Md., the classes give her a broader base of knowledge useful in and outside her job.
"They give me more than I need to know for my job," she says. "But now I can go into the woods and tell my kids this is a certain plant, and I can teach the people at work about plants."
Like Ms. Metler, many who sign up for horticultural and natural history classes also love to garden.
"There are also people who want to know more about plants or young homeowners who want to start a garden and want to do it right," says Diane Lewis, program coordinator at Brookside Gardens in Wheaton, Md.
At the Morton Arboretum in Chicago, Michael Kost, manager of natural history education, was surprised to discover that many students signed up because "they are looking for something more meaningful in their lives."
In Spring Flower Identification, an evening course Mason teaches for the United States Department of Agriculture (see story, left), the motives are varied.
Some developed an interest through gardening; one bird watcher wants to know more about the surrounding ecosystems; two others are involved in environmental sciences; and the rest signed up because, as student Pattie Kingerey puts it, "I'm tired of not knowing what I'm seeing."
The frustration applies equally to those strolling through a city park. William Schiller, resident botanist at the American Museum of Natural History in New York, has made a career of shedding a new, biological light on Central Park. In the heart of Manhattan, "we have the last significant stand of American elm trees," he likes to tell people who have signed up for his Urban Forest Walking Tours.
Ms. Lewis of Brookside Gardens likes to pepper her talks with the history and the edibility of plants. She points out that garlic cress may be a weed, but "it's great on ham sandwiches. Not that I recommend people eat everything," she adds.
Back at Carderock Recreational Area in Great Falls Park, Md., Mason examines the plants with only touch, sight, and smell. "It's not enough to say that a plant has opposite leaves," she tells her students as they crouch over a tiny white bloom. "You have to observe as many features as you can."
In the coming weeks, they will count petals and leaves, speak in terms of pedicels and peduncles, stamens and corollas. They will note when the leaves of a plant are compound, toothed, and palmately divided.
They will marvel at the power of color and fragrance to attract pollinators, be they bees zeroing in on the yellow center of a bluet or a fungal gnat following the putrid scent emanating from any one of a variety of maroon-colored flowers. Their survival trick is to entice gnats by emulating the odor of rotting meat - gnats scramble inside to lay their eggs, coming away with a coat of pollen.
These are more than entertaining tidbits. Like so much else in these courses, they constitute keys with which students can unlock nature's secrets long after the class is over.