On most warm Sunday afternoons, Joan Hendrickson grabs a blanket and heads for Georgetown's Montrose Park, a quiet 16-acre oasis of stately rose gardens and enormous sycamore trees that is more like her "own private back yard" than a public park.

Hendrickson, who lives in Foggy Bottom and owns the dating service Georgetown Connection, chooses Montrose over the more popular 1,700-acre Rock Creek park to avoid the crowds and noise.

"This is real quiet," she said. "This is like being in the country."

While Rock Creek Park enjoys the reputation as the city's largest and most used park, tucked away are small lesser-known parks that are virtually unknown outside their neighborhoods.

These semihidden parks ranging in size from 15 acres to more than 100 acres offer many of the same amenities as Rock Creek, without the struggle to find elbow room. They contain nature walks, picnic and sunbathing areas, shade trees, brilliantly colored flowers, meandering streams, playground equipment and sports facilities.

"A lot of the neighborhood people are very covetous of these park areas" and do not want to share them with the rest of the city, said Georgia Ellard, superintendent of Rock Creek Park and other federal parks west of the Anacostia River.

The alternatives to Rock Creek Park on a hot summer weekend range from the serene hilly picnicking grounds of Fort Dupont in Northeast and the grassy riverbanks of Anacostia Park to the dense nature trails of Melvin Hazen and Glover-Archbold parks in Northwest.

In the midst of a suburb-like community near Randle Circle, Fort Dupont Park, the city's second largest, occupies 376 acres that are mostly covered with a natural hardwood forest.

It features a wide variety of sports facilities and a summer theater that attracts 4,000 to 5,000 visitors for weekend summer night concerts starring such celebrities as singer Melba Moore and jazz artist Ramsey Lewis.

Fishing and carwashing are popular pastimes at Anacostia Park, a narrow grassy strip hugging the eastern banks of the Anacostia River from the Douglas Bridge to Eastern Avenue. Boosted by $6.5 million in federal funds during the Bicentennial, the park has benefited from a recent aggressive redevelopment program.

The park has become so attractive for picnickers and sports enthusiasts that a recent informal survey by the U.S. Park Police indicated that more than half of park's visitors are from outside the District. During some summer weekends the U.S. Park Service frequently was forced to close park gates to new visitors at 2 or 3 p.m. on Saturdays and Sundays.

For Edgar Ward, a 25-year-old maintenance worker on Capitol Hill, the park is a favorite place to polish his car, eat lunch and just "relax and cool out."

"It's not a lot of people and little kids," said Ward. "At Rock Creek, it would be really crowded and cars would be jammed up."

The Kenilworth Aquatic Gardens, which shimmer in the far eastern corner of Anacostia Park, consist of paths meandering through 11 acres of ponds brimming with delicate waterlilies and lotuses and small animals.

"It's a different place. It's away from the pavement," said Pepita Kauffman of Arlington. Like most visitors, Kauffman noticed the gardens on a tourist map and hopes to return in the summer when the waterlilies are at their peak in color.

On the western side of the Anacostia River, Fort Totten Park, the namesake for a nearby subway station, can be found in the midst of a quiet residential area in upper Northeast. Located between North Capitol Street and the B&O Railroad tracks, Fort Totten Park has gentle slopes and ridges dotted with chestnut oaks, pine, wild cherry and greenbriar.

Fort Totten is one of 19 Fort Circle parks that originated from a string of 68 original forts ringing the city during the Civil War as protection against Confederate attacks. By the early 1930s, the National Park Service assumed authority for managing the Fort Circle parks and other federal parks in the District that total nearly 6,500 acres.

With few picnic tables and no barbeque grills, Fort Totten is simple and natural.

"We want people to enjoy their natural surroundings," said Ellard. west of the Anacostia River. "Picnicking is just an accessory. Any more development in these parks would be inappropriate. It would destroy the purpose of the land."

The desire to keep things natural is more apparent in three Northwest parks: Dumbarton Oaks, Melvin Hazen and Glover-Archbold.

"It's absolutely a little gem, a jewel," said Marjorie Matthews of Foxhall Village said after a hike through Dumbarton Oaks Park's 27 acres with shaded walks and a small cascade of waterfalls.

Ketch Ryan, 32, who jogs around the park three times a week and lives in an apartment building whose par,king lot backs up to Melvin Hazen said,"It's my back yard." Tall tulip poplar, beech and white oak trees grace the forested tract, with May apple, spring beauty and mosses and ferns in abundance.

Hikers through the 183-acre Archbold Park have spotted foxes during treks along the park's 2.5-mile nature trail.

Some of the natural pristine charm of these federal parklands has been soiled by recent reports of drug use in the parks.

One Park Police ranger singled out Kenilworth Aquatic Gardens as "a beautiful park in the wrong place" because of the drug activity on nearby Eastern Avenue.

Burnice Kearney, superintendent of the federal parks east of Anacostia River, added, "It's a problem, but it's not a problem that's unique to the parks."

Ellard said, "I don't know any any rampant drug use. I think the parks are the safest areas in the city."

Pearl Fuchs, a retired Army colonel, lives in the Watergate complex across from Rock Creek Park but frequents Montrose Park because of her dog, Cyrano.

Fuchs said she perfers Montrose to Rock Creek because "Cyrano doesn't like the traffic and neither do I."