Millfoil
Aquatic plants are a common type of flora found in lakes and ponds that occur naturally in the northeastern region of the United States. In fact, most of these plants are a healthy and vital part of the water environment. However, one species of introduced millfoil (Myriophyllum heterophyllum) has taken extremely well to warmer ponds and lakes, where it out-competes many native species. Twoleaf millfoil is characterized by a long reddish stem and very fine leaves, which grow on or just below the surface. The plant is believed to be transported overland to new places by recreational boats and once established is very hard to remove.
Crabgrass
If you have a lawn, there are a variety of plants that may frequently invade it. Some of the more notable weeds include the common dandelion, several types of clover, fleabane, bluestem, buttercups and of course the ever-present crabgrass, Digitaria sanguinalis. Of all of these, the crabgrass may be most troubling because it is so hard to get rid of. In general, crabgrass is a low, spreading herb that produces long, flat leaves and many side shoots that help anchor the runners to the ground. Often crabgrass expands from a central point in a star-shaped pattern.
Rugosa Rose
Though originally found in Japan, Korea and China, the beach rose (Rosa rugosa) grows wild in many areas around the USA. Also called the rugosa rose, this plant is a hearty, salt- and cold-tolerant shrub that has become a common sight along the coastal regions of the Northeast. Not only does this rose put on a showy display of summer flowers, but the flowers develop large "rose hips" right below the petals. These bulbs contain rich plant material that, because of a high concentration of vitamin C, are often used in the production of herbal tea. The "hip" can also be eaten raw or made into a tart jam.
Purple Loosestrife
Today, purple loosestrife, Lythrum salicaria, is a common flowering plant of the continental United States that frequently graces roadsides and wet habitats. According to Dr. Bernd Blossey, the weed first arrived in New England during the 1830s as a contaminant in ships' ballasts or as a commercially-available medicinal herb. From these sources the perennial plant began to flourish along travel routes, especially in places with wet soil. Today, the attractive plant can be seen blooming along many Northeastern byways and, although it does crowd out native plants, its showy flower is sometimes enjoyed by passing motorists.