Naturalist John Burroughs called it "the marriage of frost and sunshine" and "the sweet goodbye to wintertime."
He was talking about maple sugaring, a spring rite celebrated yesterday by hundreds of people gathered at the seventh annual Maple Sugaring Festival at Hashawha Environmental Appreciation Center near Westminster.
Loren Lustig, the center's administrator, explained how maple trees are tapped in the spring for their sap, which is boiled down into syrup.
"Trees eat sunshine. They gobble it up," he told a crowd that included many children. "We take a little bit of the sap and make magic happen."
Volunteers in the next building served treats like vanilla ice cream with real maple syrup. "That's my hello to springtime," Mr. Lustig said.
Outside, sap dripped into buckets hung from two taps in a large maple tree. A caldron of boiling sap bubbled over a wood fire, and onlookers were given tastes as the clear sap condensed slowly into the familiar sweet syrup.
"To me, the smell of springtime is sugar water boiling. That's why I came," said Helen Englar of Westminster.
She grew up on a farm in Garrett County, where her father owned and tapped a maple grove.
Ms. Englar said those trees were cut for timber in the 1940s, but as a girl she would bring her father supper as he watched over the boiling sap. "He couldn't leave long enough to go for a meal sometimes," she said.
Nearby, teams of horses and mules provided free wagon rides, sponsored by the Maryland Draft Horse and Mule Team Association. At several booths, artisans demonstrated wood-carving, furniture-making and other skills.
Gary D. Anderson, a blacksmith from Spring Grove, Pa., made a ladle and some nails as children surrounded his 125-year-old hand-pumped forge.
Yesterday's 52-degree weather was ideal for a sugaring festival. Maple trees only produce sap on warm spring days when nights are below freezing.
In the winter, sap drains out of trees to let them survive the cold. In the spring, the sap rises, carrying with it mineral salts and sugar to give the buds energy to open and grow.
Not everything sold as syrup is real maple syrup, Mr. Lustig said. Some store brands contain only 2 percent or 3 percent real maple syrup, and some don't contain any.
As part of his presentation, he conducted a blind taste test with a volunteer from the audience, Naomi Zvirzdin of Owings Mills, who drew loud cheers when she immediately identified the real maple syrup from among three samples. She said the others tasted like corn syrup.
At one stand, "Mr. Maple Sugar," Richard N. Brown Jr. of Springfield, Va., sold maple syrup, maple candy, and maple cream. He handed out samples of maple syrup in several grades, ranging from the finest fancy grade to commercial grade, which is used to flavor chewing tobacco.
Mr. Brown said maple-syrup sellers often sell inferior grades as top quality. He said he only sells syrup from two producers who label it accurately and package it properly.
He said maple syrup is still produced commercially in the mountains of Western Maryland.
Maple syrup is expensive. Mr. Brown said a tree will produce only five to ten gallons of sap a year, which yields only one pint to one quart of syrup. He passed out samples of commercial grade syrup, followed by samples of the fancy-grade product, and said: "To me, this is what maple syrup should taste like."