Do you remember those halcyon autumn days of yesteryear, when a crisp tang in the air signaled Mother to pack a picnic and Father to fuel up the family gas-guzzler for a Sunday jaunt to the mountains to admire the fall colors?

Do you remember, I mean of course, last year, when gasoline prices hovered just below a trifling $1.90 per gallon and tanking up for a weekend drive to the country wouldn't set you back the equivalent of the GDP of a developing nation?

You may be wondering whether the only place you'll likely be seeing red this fall is at the gas pump. Happily, whether you prefer to take in your seasonal splendor by road or by water, in tent or on horseback, by bicycle or even by biplane, our region offers an abundance of destinations, all surprisingly close, where you can get outside and get some autumn.

Know Your Science

But first, a pop quiz: Why do our deciduous trees lose their leaves in the fall?

"Primarily to conserve water," says John Scrivani, resource information director for the Virginia Department of Forestry. (Don't worry, I didn't know the answer either.) Trees suck up water in the summer, and those broad, green leaves transpire a lot of it -- that is, breathe it out into the atmosphere. Once its leaves are shed, the plant can more easily survive the winter, when water is more likely to be scarce because it's frozen in the ground.

That's the short answer to the question. And it's the shorter hours of daylight that trigger a tree to begin its shift from industrious photosynthesis factory of summer to dormant, bleak and bare-branched metaphor that has launched a thousand lines of poetry.

In between, we get the evanescent glory of autumn color, those saucy scarlets and fiery oranges, bright golds and deep purples. Strictly speaking, the leaves don't really change color, they just lose some -- the green from the chlorophyll, which the trees stop making. "The colors are actually there the whole time," Scrivani explains. "It's just that the green color that has been masking them goes away.

"Warm, sunny days and cool, crisp nights without a heavy frost help speed up the process of breaking down the chlorophyll," he says.

Though it's not easy to predict exactly when the colors will peak, the eastern United States, Scrivani says, "is one of the notable areas in the world in terms of fall colors. That's when our hardwood forests are showcased the most. It's a great time to be outdoors."

For more on why deciduous trees in wintry climes lose their leaves in autumn, visit www.earthsky.com/earthcare/shows.php?s=o&date=20041122.

VIRGINIA DEPARTMENT OF FORESTRY -- www.dof.virginia.gov/info/fall-foliage-map.shtml. Learn more about leaves and get fall foliage reports and recommended foliage trips.

MARYLAND PARKS FALL FOLIAGE UPDATE -- www.dnr.state.md.us/outdoors/fallfoliage.

Name That Tree

If all this talk of chlorophyll and leaf biology has put you in a studious frame of mind, you might start your own autumn journey at one of Virginia's best-kept secrets, the state arboretum in Boyce, on the edge of the Shenandoah Valley in Clarke County.

"So many people say, 'Wow, the state arboretum! Where is that, in Richmond?' " says Tim Farmer, the arboretum's public relations coordinator. "And I explain that it's about two hours north of there, so much closer than people realize" to the Washington area.

The arboretum offers miles of pathways, including a five-mile bridle trail (bring your own horse), for roaming among its more than 8,000 trees and woody shrubs. "Most everything close to the public areas is well labeled," Farmer says, "so you see more than pretty trees -- you actually learn something. We have beautiful walking trails, including a native-plant trail through woodland, wetland and meadow areas, with a series of interpretive signs to explain the native plants and trees."

For fall color, "we have the largest grove of ginkgoes planted for research outside of their native China," Farmer says. "Usually by the first weekend of November they turn a beautiful gold. Also, we have a beautiful collection of maples that are spectacular." Autumn's other attractions at the arboretum, he says, include "the nice views of the Blue Ridge as the summer haze drifts away. We are also on the Virginia Birding and Wildlife Trail, and a lot of the raptors use the ridges for migration this time of year, so we are seeing a lot of birds."

Although the crowds are flocking to the usual leaf-peeping haunts, the arboretum's quieter reputation means that "depending on when you come, you can kind of have the place to yourself," Farmer says. "The best part is we are open dawn to dusk, 365 days per year."

If, however, you prefer your trips, and your trees, a lot shorter, you could instead visit the U.S. National Arboretum in the District. In addition to its 446 acres of woods and trees, the National Arboretum is home to the National Bonsai & Penjing Museum, where an exhibit from Oct. 29 through Nov. 6 will feature deciduous bonsai from the museum's permanent collection and "the autumn coloring of leaves and the ripening of fruit," according to the arboretum's Web site. Exactly how many bonsai apples would it take to make a pie?

STATE ARBORETUM OF VIRGINIA -- 400 Blandy Farm Lane, Boyce, Va. 540-837-1758. www.virginia.edu/blandy/home.html. Open dawn to dusk daily year-round. Free.

U.S. NATIONAL ARBORETUM -- 3501 New York Ave. NE. 202-245-2726. www.usna.usda.gov/index.html. Open daily, except Christmas Day, from 8 to 5. The National Bonsai & Penjing Museum is open from 10 to 3:30. Free.

Hit the Trail

With bright blue skies above and the crunch of leaves underfoot, a perfect autumn afternoon calls for rambling, whether your inclinations run to strenuous hikes or leisurely saunters. In Delaplane, in Fauquier County west of Middleburg, Sky Meadows State Park gives you your choice, with the added attraction of "an amazing panoramic view of the mountains," says Kathy Nations, who directs the park's interpretive programming. "We have trails that are especially designed to enhance those views," she says, and one of Sky Meadows's six hiking paths also connects in less than a mile to the Appalachian Trail. (In case you're feeling ambitious, it's a three-day hike to Harpers Ferry, W.Va., and two days to Shenandoah National Park.)

This weekend and next, Sky Meadows will host a Fall Farm Fest at Mount Bleak House, the cheerily named historic farmhouse within the park that has been restored to depict daily life as it was lived there in the 1860s. You can pick your own pumpkins at the Farm Fest ("and check out a pumpkin kit and carve it," Nations says), take a tour of the house and, on Oct. 29 from 1:30 to 3, learn about the raptors you might see soaring overhead, with a program from the Raptor Conservancy of Virginia.

"Right now, the fall foliage is starting to peak," Nations says. "It is quite beautiful."

Not to be outdone in either the natural beauty or aerobic challenge departments, the National Park Service's Rock Creek Park has 32 miles of trails, "and you totally forget that you're right in Washington, D.C., because once you get out on the trail, you don't hear cars, you don't hear noise, you're really in the wilderness," says park ranger Lora Williams. Apparently the park's human visitors aren't the only ones to appreciate the wilderness either; in the past year, coyote sightings have been confirmed within the park. Perhaps you might catch your own fleeting glimpse of a ghostly gray figure slipping into the shadows if you join a ranger Oct. 30 for a three-mile hike focusing on fall changes in the park, leaving from Rock Creek's Pierce Barn (across the parking lot from Pierce Mill) at 9:30 a.m.

Speaking of canines, we all know who's really yearning for a frolic in the falling leaves, and if tails could talk, the one wagging hopefully at you right now would be saying, "Surely you're not thinking of leaving me behind?"

"Hiking with a dog, in addition to giving you an enthusiastic hiking companion, also gives you a different perspective on the trail," says Jeff Bolognese, coordinator for K9 Trailblazers, a dog-hiking club in the Washington-Baltimore area that holds monthly group hikes for leashed dogs and their human companions. (K9 emphasizes, and park rules usually require, that dogs remain on leashes at all times during these outings.) "Dogs notice things that we might not (scents, animal tracks and so forth), and seeing them interact with the natural world expands and enriches how we see that world," he says.

Bolognese recommends Sugarloaf Mountain in Dickerson, Md., in Frederick County, as "one of K9TB's all-time favorite hiking spots." There are a variety of hiking trails, and "fall is an especially nice time to visit," he says. "The changing colors are beautiful, and many of the hiking trails offer scenic views of the surrounding country."

SKY MEADOWS STATE PARK -- 11012 Edmonds Lane, Delaplane, Va. 540-592-3556. www.dcr.state.va.us/parks/skymeado.htm. The Fall Farm Fest is Saturday and Sunday and Oct. 29-30. A Holiday Home festival is Nov. 26 through Dec. 4, featuring Virginia foods and products. $3 weekdays, $4 weekends through Oct. 31; $2 Nov. 1 through March 31.

ROCK CREEK PARK -- Pierce Barn, Tilden Street and Beach Drive NW. 202-282-0927. Morning Fall Hike, for ages 8 and older, leaves at 9:30. Free. For other hikes, programs and activities, visit www.nps.gov/rocr/schedule. Visitor information (Wednesday through Sunday), 202-895-6070. www.nps.gov/rocr. Free.

K9 TRAILBLAZERS -- www.k9trailblazers.org. A schedule of upcoming hikes, a pocket guide to hiking with your dog and a list of dog-friendly hiking destinations in the Baltimore-Washington area.

SUGARLOAF MOUNTAIN -- 7901 Comus Rd., off Route 109, Dickerson, Md. www.sugarloafmd.com. 301-874-2024. Open from 8 a.m. to one hour before sunset. Free.

Float Your Boat

Paddles and lifejackets seem more your style than walking sticks and blistered feet? No experience is necessary to take part in the fall color paddling tours at Pohick Bay Regional Park in Lorton.

"We do a little bit of instruction at the beginning before we get on the water, and it's all flat-water paddling," says Assistant Park Manager Laurelyn Rawson. Paddles, boats and lifejackets are provided, and participants need bring only water and a snack. (Sunscreen, bug spray and a hat are good to have, too, and remember your binoculars as well.)

"We lead the tours back into Pohick Bay. A huge portion of Mason Neck is parklands, so there is a lot of protected land out here. With the park on one side of the bay and Fort Belvoir on the other, with no development on their side, you feel like you are in a different world," Rawson says.

Bald eagles are often spotted on morning paddles in particular, along with blue herons, white egrets, fish and beavers. Rawson expects the best fall colors in the woods and marshlands in the next few weeks. "The end of October, beginning of November, it should be really spectacular."

To the east in Upper Marlboro, Patuxent River Park's Kayak Kaper on Saturday is another guided, no-experience-necessary paddle trip, this one exploring tidal wetlands of the Patuxent River.

For the more independent-minded, both parks have boat launches that are open all year. An extensive list of additional area launch sites can be found on the Chesapeake Paddlers Association Web site at www.cpakayaker.com/launchsites.html.

POHICK BAY REGIONAL PARK -- 6501 Pohick Bay Dr., Lorton. 703-339-6104. www.nvrpa.org/pohickbay.html. Fall color paddles Oct. 29 and 30 and Nov. 5. $25 per person. Park admission: $7 per vehicle; annual pass $25. Free for residents of Arlington, Fairfax and Loudoun counties; and Alexandria, Fairfax City and Falls Church; no fee after Oct. 31. Boat rentals available through Oct. 30; car-top boat launch open year-round, $3.50.

PATUXENT RIVER PARK -- 16000 Croom Airport Rd., Upper Marlboro. 301-627-6074. www.pgparks.com/places/parks/patuxent.html. Annual park pass $2.50 for residents of Prince George's and Montgomery counties, $5 for nonresidents; good through Dec. 31. No launch fees. Kayak Kaper for ages 12 and older Saturday from 9 to noon. $15 for residents, $18 nonresidents.

Sleep Under the Stars

While the days are still warm but the nights are growing cooler, it's prime camping season, and if there's anything better than snuggling down in your sleeping bag as the falling leaves brush softly against your tent roof, it's snuggling down in your sleeping bag and knowing that if you wake up to a driving rain hammering down overhead, you're only a half-hour from home, a hot shower and a dry bed.

The family campground at Prince William Forest Park, which borders the Quantico Marine Corps Reservation in Prince William County, is open all year for tent-camping and recreational vehicles 32 feet and smaller, set among what the park's Web site notes is "the largest example of eastern piedmont forest in the National Park System."

Typically peaking in the last two weeks of October, "the fall colors are beautiful," says the park's assistant superintendent, George Liffert. More than 36 miles of hiking trails, a nine-mile paved loop road open to bicycles and vehicles, nine-plus miles of fire roads for mountain biking, several small lakes, and both Quantico Creek and South Fork Quantico Creek invite you to explore a range of habitats and natural areas.

"It's a great place for bird watching, and there's a diversity of wildlife," says Liffert, including the familiar squirrels and white-tail deer, wild turkey, fox, bald eagles and even the occasional coyote and black bear.

PRINCE WILLIAM FOREST PARK -- Triangle, Route 619 west. 703-221-7181. www.nps.gov/prwi. $5 daily entry fee; $20 annual pass. Family campground, $15 per night. Back-country primitive camping by permit.

Put the Top Down

Want the wind in your hair? If you're going to blow three bucks a gallon driving to see the leaves, you might as well do it in style, and nothing says "carefree Sunday drive" like a 1957 Austin Healey convertible. Or a 1960 Triumph TR-3. These and a variety of other classic sports cars can be yours for an afternoon or a weekend, courtesy of Sports Car Rentals in Batesville, Va.

A bit farther afield than other destinations in this story, Sports Car Rentals is a short distance southwest of Charlottesville in Albemarle County. Nevertheless, if you've ever dreamed of hugging the curves of a country lane at the wheel of a vintage sports car as the brilliant colors of autumn swirl in your wake, this one could well be worth the trip.

"This area is really uncrowded, so people can hit the back roads and really have a ball driving the cars," says owner John Pollock, who offers customers a map of his favorite local driving roads. Many people choose to head for Skyline Drive or take a tour of the many local wineries (with a designated driver along, of course).

Closer to home, you can take in the fall scenery from an entirely different point of view -- about 4,000 feet up, from the open cockpit of a jaunty, red and white 1942 WACO (pronounced "wah-ko") ZPF-7 biplane.

Don't worry that the WACO's first logbooks were noted as "lost in inverted flight"; owner John Corradi is an experienced pilot who flew first with the Navy and then for more than 30 years with United Airlines. Book a trip with Blue Ridge Biplane Rides, and Corradi will take up to two passengers on a flight from near Culpeper, over the Blue Ridge toward Front Royal, down along the Shenandoah River and back over the mountains around Luray.

"The fall season is my busiest time," Corradi says, and "morning and evenings are the best because of the light; it's so pretty, and the air is so smooth."

SPORTS CAR RENTALS -- Plank Road, Batesville, Va. Route 29 south to Route 692 west. 434-823-4442. www.sportscarrentals.com. Vehicles are $95 per day or $180 per weekend. Weekly rentals and gift certificates available. There is a no-fee cancellation policy in case of bad weather.

BLUE RIDGE BIPLANE RIDES -- 17586 Ryland Chapel Rd., Rixeyville, Va. 540-937-5371. www.blueridgebiplanes.com. Hour-long Skyline Drive flight, $400. Half-hour tours, $250.

Do Some Good

When only a short drive, or even a Metro ride, can deliver you to woods or open waters, to a day hike or overnight adventure in the outdoors, it's easy to see how blessed we are by the local bounty of our parks, mountains, forests and open lands. So it's nice to know that you can give back by volunteering even while you're getting the benefits of the season's beauty. Local chapters of the Potomac Appalachian Trail Club, which helps protect and maintain a stretch of the Appalachian Trail from Shenandoah National Park in Virginia through southern Pennsylvania, regularly sponsor work days for trail maintenance and upkeep along the route.

Nancy Hammond of the North Chapter, based in Maryland, says: "Before I did this, I used to wonder why the Appalachian Trail was in such good shape. Then I got involved in trail work, and I found out that it's because people work really hard to keep it that way." Though some volunteers prefer summer and others winter, "This is the time of year that we can all agree on," Hammond says. "We are usually out from morning to mid-afternoon, and as long as you're reasonably fit -- if you're comfortable hiking two to five miles -- you can do the work."

You don't have to be a member of the club to participate, "but once people come out and see how fun it is, we sure hope they will join," Hammond says.

POTOMAC APPALACHIAN TRAIL CLUB -- 118 Park St. SE, Vienna. 703-242-0693. www.patc.net. For scheduled trips, events and programs, and contacts for trail work days, visit www.patc.net/activities/forecast.html. Call the activities information line, 703-242-0965, for trips for the upcoming week. Nonmembers are welcome on all trips. Inquire about work days at least one week in advance.

Caroline Kettlewell is a freelance writer and regular contributor to Weekend. You can find her online at www.carolinekettlewell.com.

In Clarke County, the grove of ginkgoes at the State Arboretum of Virginia turns gold in autumn. Miles of trails offer plenty of opportunities to view the changing leaves.