At the beginning of summer, Pat Vogel of North Patrick Henry Drive in Arlington spotted a four-inch tall, umbrella-shaped plant fighting for its place in the sun among her garden's border of dainty pink and white impatiens.

Now, 10 weeks later, the baby is a monster. The giant weed towers more than 13 feet -- all the way up to the second-story bathroom window -- with a branch spread of 6 feet and a stem 2 1/2 inches thick at the base.

Vogel, whose gardens cover half her back yard and include vegetables, 50 azalea bushes, three dogwoods, and a Norway maple, knew it was some sort of weed. "But it looked so attractive I left it," Vogel said.

"It's supposed to be my tomato bed," she said as she pointed to the patch of earth between her house and the concrete walkway where the weed reigns. But the tomato plants, pushed up against the brick wall of the house, have become the garden's secondary attraction. "The tomatoes are shriveled up on account of the plant. Normally they're the size of potatoes," Vogel claimed.

Neither Vogel's husband Anthony nor any of the neighbors could identify the plant. Her daughter, knowing a weed when she saw one, advised her to yank it out. A visiting relative was afraid it would flower, go to seed and infest the neighborhood, Vogel said.

Anthony Vogel, who leaves the gardening for the most part to his wife, had mixed reactions to the huge plant with the five-lobed leaves. "Up to two weeks ago, he said, 'Take it out, take it out.' Now, my husband doesn't care whether it's there or not," Pat Vogel said.

"I would have pulled it out a long time ago," she insisted.

Vogel grew up in Australia, a land known for its unusual animal and plant life, but she had never seen any plant grow so quickly. When the weed reached 10 feet and showed no signs of slowing, she took a cutting to the Arlington branch of the Virginia Cooperative Extension Service.

"One woman said it looked like a marijuana plant," Vogel recalled.

Finally, Bruce Whiton of the Extension Service's Alexandria branch resorted to a key to positively identify the plant.

"Palmate, three to five lobes. Rough, hairy above; rough, hairy below. Strong tasting," Whiton read from "Weeds of the Northeast." He broke the plant stem and touched it to his tongue. "I guess you could call it strong tasting," he said.

Whiton identified it as a giant ragweed (ambrosia trifida), which can grow to a height of 18 feet.

Common ragweed is only three feet high, but short or tall, an acre of ragweed can produce a ton of sneeze-inducing pollen between mid-August and the first frost.

An acre of ragweed? Hayfever sufferers would shudder at the thought. Could Vogel's plant be the start of a giant ragweed infestation in Northern Arlington?

Probably not. The giant ragweed is an annual; that is, it dies every year. And because it has a shallow root system there is little chance that giant ragweed will take over Arlington the way kudzu reclaimed the South, according to Whiton.

Dr. Wayne Bingham, a weed specialist at Virginia Tech in Blacksburg, said the giant ragweed is fairly common in Virginia, Maryland and North Carolina.

"It grows in rich places like river bottoms, but it can be found along roadsides in low places where the soil is pretty good," Bingham said.

But whether Vogel's weed is common or not, she said that she's gotten used to looking at it through her kitchen window in the early morning sunlight. It was only after a number of suggestions from her family that Vogel even considered getting rid of the plant. In fact her husband repeatedly offers to pull out the now leaning ragweed.

"He has a poor outlook on plants," Vogel joked. "I'm going to leave it there a little longer. I'm the boss of it," she said.