Plants to Watch Out For

Invasive plants are introduced, non-native plants that have the potential to cause harm to the environment or the economy. Non-native species cost billions of dollars each year to the United States economy. Invasive species threaten native species and cause a greater risk to threatened and endangered species. These invasive plants may out-compete native plants for nutrients, space, and sunlight that are necessary for plant survival and may even create a monoculture. They can even change the food web by destroying or replacing native food sources, and they often provide very little to no food value to wildlife.

Check out the invasive plants below to make sure these common invasives are not lurking on your property!


Grasses

Reed Canarygrass (Phalaris arundinacea)

This cool season grass is large and coarse with erect, hairless stems that can reach up to nine feet in height. It has gradually tapering leaves that are 3.5 to 10 inches long. The upper and lower surface of the leaves is rough in texture. Coloration can range from a light green to a straw color.

Common Reed (Phragmites australis)

This tall, warm-season, perennial grass has erect, rigid, smooth, and hollow stems. It can grow up to 6 meters in height. The leaves are stiff, lanceolate, and are 20-40 cm long and 1-4 cm wide. This species flowers between July and October, and the flowers are arranged in tawny spikelets with tufts of silky hair. The hairs are purple in color but become tawny to dark brown when mature. The seeds are thin, brown, and delicate and have long, narrow bristles.

Japanese Stiltgrass (Microstegium vimineum)

This summer annual grows to be 1.5 to 3.25 feet tall. The culms are branched and decumbent below, while above they are mostly unbranched and erect. The culms are green to reddish purple, free from hair, and terete. There are several alternate leaves that occur along the entire length of each culm and its subdivisions. The leaf blades are 1.25 to 4 inches long and flat.

Herbaceous

Garlic Mustard (Alliaria petiolata)

This biennial herbaceous plant has a weak single stem that reaches 12 – 13 inches in height during its second and flowering year. The leaves are round, scallop-edged and dark green. During its first year, it has rosettes of 3 or 4 leaves. In the second year, plants have alternate leaves on the stem. The leaves and stems smell like onion or garlic when crushed. The flowers are white, small, and numerous.

Shrubs

Amur Honeysuckle (Lonicera maacki)

This shrub typically grows to be 10-15 feet tall, though it can reach higher heights if not dealt with. It can form dense, shrubby, understory colonies that completely eliminate the native woody and herbaceous plants underneath. The leaves are medium to dark green in color and approximately 3 inches long. Fragrant, white flowers will bloom in May and June. These will then turn into juicy, dark red berries that are consumed by bird species.

Autumn Olive (Elaeagnus umbellata)

This invasive shrub typically grows to be 10-16 feet tall and 20-30 feet wide. It grows rapidly and can form dense, impenetrable thickets. The twigs are speckled and a silvery or golden brown, while the leaves are a grayish green with distinctive silver scales on the underside. It produces clusters of fragrant silvery white to dull yellow flowers between late April and early June. The fleshy, abundant, scale-dotted fruits become red when ripe in the early fall and are eaten by birds that disperse the seeds.

Burning Bush (Euonymus alatus )

Burning Bush is a dense, multi-stemmed shrub that is noted for its fiery red fall foliage color. It will grow to be approximately 15-20 feet tall. This plant produces small, non-showy, yellow-green flowers in May. Small fruits will appear green at first but will ripen to a red color in the fall. The seeds encased in the fruits attract birds that eat and disperse them. The twigs have corky, winged ridges that are more noticeable after leaf drop.

Multiflora Rose (Rosa multiflora)

Multiflora rose can form dense, impenetrable thickets that tend to eliminate native plants if not managed. In some cases, it can even render land virtually unusable. It spreads through self-seeding, root sprouts, and stems that root in the ground. This plant has a prickly cane that can grow to 15 feet in height. It will produce small, fragrant white or light pink roses that bloom in one profuse display in June. The flowers are replaced by small, red hips in the early fall that persist into winter.

Trees

Callery Pear (Pyrus calleryana)

Callery Pear has many varieties and can grow up to 50 feet or more. It has alternate branching, and the leaves are generally ovate-shaped. This tree produces many white flowers in the spring, which makes the plant very showy. The twigs may have long thorns, and the fruits are in tiny clusters. The fruits resemble tiny, brown apples with rusty speckles and are persistent into winter.

Tree of Heaven (Ailanthus altissima)

Tree of Heaven is a fast growing tree that can reach 60-70 feet tall. It is short-lived but continuously produces root suckers that persist long after the original tree has died. It has alternate branching and large, compound leaves. The twigs give off a strong, unpleasant odor if crushed or scraped. It also produces a chemical that inhibits other plants from establishing too close to an individual tree. This tree provides very little benefit to wildlife.

White Mulberry (Morus alba)

White mulberry is common throughout the Midwest, but it is not a native species. It is typically a smaller tree and does not reach higher than 30 feet tall. It has alternate branching, and the twigs emit a milky sap when cut. Fruits are in clusters of drupes and look similar to blackberries. The berries are eaten by fruit-eating birds and many omnivorous mammals that can disperse seeds quickly.

Vines

Asian Bittersweet (Celastrus orbiculatus)

This plant is a perennial, deciduous, twining woody vine that can grow to 60 feet in length or longer. This fast-growing vine climbs or sprawls and can easily cover, shade, and outcompete other vegetation. It can even girdle and kill large trees. Birds and other wildlife species eat the berries of this vine and disperse the seeds. This vine can be recognized by its brown straited bark, alternate elliptical to circular light green leaves that turn yellow in the fall, small greenish white flowers that bloom in May to early June, and small, round, pea-sized fruits that ripen to yellow before splitting open to reveal scarlet berries that persist into winter.

Help Slow the Spread of Invasive Species!

Make sure to remove invasive species from your property. Regularly clean your boots and outdoor equipment to remove plant materials that may spread to other areas you travel. Even though you might not see them, plant material may be lurking on your equipment. Also, remember to never transport firewood more than 30 miles as doing this increase the spread of invasives!

Check out this fun activity geared towards teaching students about invasive species!