The deciduous tree typically grows 40 to 60 feet tall. Unlike sugar maple, Norway maple produces a milky sap. The trees can also have red and purple leaves. It produces a large number of seeds that can out compete surround plants. What to do: Small trees can be mowed or hand pulled. For larger trees, removing tissue around the circumference and applying herbicide can be effective.

The purple loosestrife can grow up to 7 feet tall, but usually is about 3 to 5 feet in height. It can be spotted easily by its long stalks of purple flowers. It invades wetlands often forming dense colonies. A single plant can produce more than a million seeds. What to do: Hand pulling works for smaller populations. Repeated cutting can prevent seed production and might eventually kill the plant. Galerucella beetles have also been introduced under state supervision and have been successful.

This small tree can grow up to 20 feet. It has small shiny leaves and small dark fruit. It is native to Europe, Central Asia and North Africa. Birds can spread the fruit causes it to overcrowd fields, woodlands and wetlands. What to do: With small populations hand pulling works or mowing frequently in fields. For larger plants systemic herbicide at the cut stems or stump sprouts.This small tree can grow up to 20 feet. It has small shiny leaves and small dark fruit. It is native to Europe, Centr