"WELCOME to the Seventeenth Century," says Emily Joyner, an interpreter for the Jefferson Patterson Park and Museum in Maryland's Calvert County.

She's greeting visitors alighting from a tractor-drawn wagon. On weekdays, the tractor works in the vast fields of wheat and soybeans on this 512-acre farm. But on weekends, through Labor Day, the workday tractor becomes a sort of time machine, transporting visitors around the farm and into the past.

Joyner, dressed in homespun garb, takes a break from her toil in the kitchen garden of a 17th-century tobacco plantation known as King's Reach, to chat with wagon passengers. She begins with a barrage of questions:

"Have you ever seen a garden like this? Why is it a different shape? Why do you suppose I'm growing things in funny little hills?"

Joyner also supplies most of the answers:

"I learned how to do this kind of gardening from the Indians. In the Seventeenth Century, the woods didn't look like these woods," she explains, gesturing at the forest that borders the farmland. "The trees were much bigger. These are real wimpy trees compared to those. To clear land for farming, they'd slash a ring around the bottom of the tree and wait for it to die. The branches would die first, and wherever the light came through, they'd make a garden. They had no draft animals, so they'd hoe the rich topsoil into little hills."

In the little hills, Joyner is growing corn, beans, squash and Jerusalem artichokes. This garden, she tells us, is just to give us an idea of what a colonial garden is like.

"This is too tiny," she says. "A real Seventeeth-Century kitchen garden would be ten times this size and have room for additional crops, including sweet potatoes, herbs and melons."

The corn is ground into meal in a rough-hewn mortar and pestle, and Joyner invites all the children on the wagon tour to have a crack at it. The meal would be used to make corn bread because "I can't just run down to High's and get a loaf of bread."

The roughly hexagonal plot also contains a plant that visitor James Taylor, 9, correctly identifies as tobacco.

"Why am I growing that?" asks Joyner. "I can't eat it . . . That's my money. I pack it into hogsheads and roll it down to the river and it goes to England with my shopping list."

Among the things the tobacco buys are simple tools, such as the hoe Joyner is using, and shoes, which she isn't wearing.

"It's okay not to wear shoes," she says, showing a dirt-streaked bare foot. "My shoe leather has to come from England. It's precious. I save it for the winter."

As Joyner goes back to cultivating her garden, archeologist Trish McGuire, who is acting as tractor-driver and guide, takes us to the site of the plantation house. Although there are plans to do a partial reconstruction of the house, all that is there now are the pits dug by the archeologists, now covered with plastic held down by old tires, and an artist's conception of what the house looked like. If "plantation" connotes Tara, think again. King's Reach, the name given to the plantation by the archeologists, was a two-room,story-and-a-half wooden house with a sleeping loft. Attached was a small "quarter" for slaves or indentured servants.

"The site was excavated in 1984 and 1985," says McGuire. "We located it in this plowed field by walking transects . . . We collected artifacts from every four-meter square, and mapped what we found."

When the archeologists found a high concentration of pipe stems, ceramics, nails and glass, they knew they'd hit paydirt.

"That first summer we got down to subsoil and found the remains of the house and the post holes . . . Wood rots and leaves a mold of the fence post," says McGuire. "In '85, we began to excavate the cellars."

The archeologists also found a "borrow pit," where the settlers had dug clay to make the chimney; later the pit was filled with oyster shells and wine bottles, evidence that not all was toil in the 17th century.

"One thing you're probbly all wishing for right now, how do you think they got water?" asks McGuire.

One child points to the Patuxent River while another indicates "that little white building," which is actually a portable toilet.

The water, McGuire answers, was hauled from a spring in the woods, and there were no toilet facilities. The archeologists found no traces of outhouses or chamber pots.

Leaving that mystery unresolved, we journey back even further in time to the site of an Indian village that Captain John Smith, who sailed past on the Patuxent in 1607, mapped as Quomocac. At this site, excavated last summer, archeologists found a kernel of corn that has been carbon-dated to 1350 AD. Other archeological evidence shows that the Indians were growing corn, beans and squash on what is now Patterson Park at least by 900 AD.

After all, the Indians couldn't run down to High's for groceries either. GOING ON THE WAGON --

Free wagon rides around Jefferson Patterson Park start Saturdays and Sundays at 11:30 through Labor Day weekend. The ride takes about 45 minutes, and additional trips are offered throughout the afternoon. Costumed presentations, such as Emily Joyner's garden demonstration, alternate with programs on Indian hunting techniques, animal husbandry, tool manufacture and other facets of 17th-century life.

The park is open Wednesday through Sunday, April 15 through October 15. It offers several trail walks, picnic facilities and a small museum. 301/586-0050.

TO GET THERE --

Take Maryland Route 4 south from the Beltway to Route 264. Turn right and continue to Route 265. Turn left and continue to the park entrance. It's about a 1 1/2-hour drive from Washington.