I would like to add a weedy plant that was not mentioned as a warning to gardeners: Sedum acre, which is also called wallpepper.

The gulls bring in the seeds of weedy plants.

A weedy plant known for its tiny sharp-needled seeds.

On sites dominated by Imperata cylindrica or other weedy plants, weed control is necessary in the first 1-2 years to ensure establishment.

Pondweed, a weedy plant found in shallow freshwater.

Overwintering can take place in dead leaves, mummified fruits, under buds or on weedy herbaceous plants near the host.

Chenopodium album is a fast-growing weedy annual plant in the genus Chenopodium.

Pigweed can mean any of a number of weedy plants which may be used as pig fodder:

They clear out weedy plants and help seeds to grow so that future generations will be able to enjoy our native wildflowers.

All are beautiful in their own right but all are aggressive weedy plants taking over and replacing the local native flora.