Invasive Tree Species

Flashcards about Invasive Tree Species and related topics.

Norway Maple (Acer platanoides)

Broken leaf stems ooze white sap; seed wings angle is approximately 180°; bark is regularly grooved; flowers appear in early spring before leaves.

Sycamore Maple (Acer pseudoplatanus)

Five lobed leaves with lightly serrated edges; leaves are typically 3-6” wide, have deep veining and feel a bit leathery; bark is gray-brown to red-brown and typically breaks into large scales.

Tree-of-Heaven (Ailanthus altissima)

Leaves are 1-4’ in length with notched base on each leaflet and large leaf scars on the twigs; twigs may have a strong peanut butter-like odor when broken; fruit is an oblong, twisted samara hanging in long clusters.

European White Birch (Betula pendula)

Smooth twigs; triangular leaves with double serration on the edges; bright white bark often with scattered black fissures; buds are slender, pointed, green and brown.

English Hawthorn (Crataegus monogyna)

Deeply lobed leaves; thorns; white or pink flowers appear in spring; fruit is a red pome with one seed inside which ripens in early fall.

English Holly (Ilex aquifolium)

Leaves are thick, glossy, dark green and wavy, 1-3” long with sharp, stout spines along edges; bunches of red, yellow or orange berries appear on female trees in winter.

Princess Tree (Paulownia tomentosa)

Leaves are 6-12” long, heart-shaped and hairy on the underside; 2” long tube-shaped purple flowers develop in upright clusters in the spring; fruit is an oval shaped capsule.

White Poplar (Populus alba)

Leaves are coarsely toothed, 2-4”, with shiny, dark green topsides and silvery-white and hairy undersides; bark on young trees is smooth and greenish white becoming gray and wrinkled with age.

Sweet Cherry (Prunus avium)

Leaves are alternate, 2-5” long, and oval with serrated edges and two obvious red glands at the base of the leaf; white flowers appear in early spring.

Black Locust (Robinia pseudoacacia)

Leaves are 8-14” long with 7-20 small round leaflets per leaf; a pair of long spines are located at the base of most leaves; showy fragrant white to yellow flowers give way to smooth 2-4” seed pods.

European Mountain Ash (Sorbus aucuparia)

Leaves are 5-8” long with 1” long individual leaflets that are serrated on their upper halves; clusters of bright deep orange 3/8” diameter pomes ripen in fall.

Siberian Elm (Ulmus pumila)

Leaves are less than 3” long, singly-serrate, and dark-green in color with a nearly equilateral base; bark is light gray with irregular furrows; fruits are flat, circular and ½” wide with a notch at the top.