Most of the readers who entered last week's Wild Guess contest correctly named the plant shown above - purple loosestrife - albeit with a variety of spellings.
In the 1800s, purple loosestrife emigrated from Europe and Asia to the U.S., where it now has been declared an invasive species in many states.
Originally introduced here for ornamental and medicinal uses, it quickly spread. A single plant can produce up to 3 million seeds in one year.
Loosestrife appears to seek out wetland habitat, spreading rapidly in wet meadows, marshes, river and stream banks, pond edges and ditches, according to the state Department of Conservation and Natural Resources.
Too often, it crowds out other species, such as the edible cattails.
Loosestrife can grow to such a wild extent that it clogs rivers and canals, impeding water flow.
The herb is a perennial, reappearing year after year. In addition to growing from seed, the plant can grow underground stems that can emerge.
It flowers from June to September and its rich purple to magenta flower spikes can top plants already 4 to 10 feet high.
In some states, purple loosestrife still is sold as an ornamental plant. However, it has been outlawed in other states, including Minnesota, Wisconsin and Illinois.
Once established, loosestrife is difficult to eradicate.
DCNR recommends that residents reject purple loosestrife and instead select native plants. The agency suggests gardeners try liatris, or blazing star, which was one reader's Wild Guess.
Liatris also sports showy pink-purple flower spikes. It, too, is a perennial and is used as a food source for certain species of butterflies.
Liatris is in the aster family.
Another guess was the herb lavender. Though lavender also produces a purple flower, the plant grows no taller than 3 feet.
Lavender is among the mint family and can be used in cooking or for medicinal purposes. Essential oils are popular in cosmetics, perfumes and balms.
"(My guess is) purple loosestrife, a very beautiful but invasive plant. But, it grows where it wants to grow. We tried to transplant some and it chose not to grow. But, on second thought, we live in the woods and maybe the deer ate them off."
Red Rock Mountain
Today's Wild Guess on F-1 will be the last flower photo. Next week we'll move onto mammals of Pennsylvania.
The winner of the monthly prize for June will be announced in the July 8 edition.