These species are not native to the State of Maine, but are not necessarily invasive; they are usually planted for ornamental purposes:

Burning Bush

Dawn Redwood

Doctor Merrill Magnolia

European Beech

European Hornbeam

Ginkgo (Female)

Homestead Elm

Japanese Tree Lilac

Japanese Zelkova

Katsura

Littleleaf Linden

Morrow’s Honeysuckle

Mugo Pine

Norway Spruce

Pin Oak

River Birch

Scots Pine

Burning Bush (Euonymous alatus): Also called winged euonymus, burning bush is native to northeastern Asia, Japan, and central China. This plant is invasive, and the National Park Service recommends it not be planted.  It was introduced to the United States as an ornamental shrub around 1860, but soon invaded the natural ecosystem, from New England and the Midwest to Florida and the Gulf Coast. It causes ecological harm by forming dense thickets, crowding out and covering native plant seedlings. It spreads through underground shoots (vegetative reproduction) and through bird dispersal of its seeds. Despite its invasiveness, burning bush is still commonly used as an ornamental planting because of its beauty. It can be identified by its corky “winged” branches, dark green leaves that turn brilliantly purple-red in the fall, and small, red, fleshy seeds.

Dawn Redwood (Metasequoia glyptostroboides): The dawn redwood hails from China, and is a deciduous conifer. Like many more familiar conifers, it grows in a conical shape, with dense horizontal branching up the trunk. It has shredded, reddish bark, and its trunk appears gnarled and braided. The dawn redwood holds its feathery, flat, deciduous needles along stems arranged oppositely from each other on the twigs, and produces bluish cones that turn brown when mature. The dawn redwood is an immensely old species; fossil record show that it existed at least 50 million years ago. It can grow up to 100’ tall, and is related to the bald cypress and the redwood.

Doctor Merrill Magnolia (Magnolia loebneri (Merrill)): This cultivated hybrid magnolia can grow from 20’ to 30’ tall, and has star-shaped, pinkish-white flowers. It is deciduous, and has narrow, oval-shaped leaves. The cultivar was first developed at Boston’s Arnold Arboretum in 1939, and was named after its former director, Elmer Drew Merril, in 1952.

European Beech (Fagus sylvatica): As the name suggests, the European Beech is native to Europe, and is planted in the United States as an ornamental. It closely resembles its American cousin, Fagus grandifolia, except the European beech’s branches often gracefully sweep the ground, giving it a very attractive form. It grows between 50’ to 70’ tall, and has smooth, light gray bark and oval-shaped leaves with rippled margins. Like its American cousin, the European beech is also susceptible to the canker-forming beech bark disease, which was introduced in Nova Scotia and has spread south

European Hornbeam (Carpinus betulus): Native to Europe, the European hornbeam can be identified by it smooth, almost muscular-looking fluted, gray bark. The mature tree will be between 40’ and 60’ in height, and have dense foliage. Leaves are oval-shaped and the edges are doubly serrate, which means hat even the ‘teeth’ have teeth. The wood of European hornbeam is very hard, and can be polished to resemble horn, as the name suggests. It was once used to make yokes for oxen.

Gingko (Female) (Gingko biloba): The ginko a living fossil. It is the only deciduous gymnosperm, and is more closely related to pine trees than other broad-leaf plants. It is dioecious, meaning it has a male and a female form. Seeds, found only on the female trees, are soft and fleshy, and not protected by an ovarian wall. Ginkos are native to China, and can grow very tall (up to 80’). They grow well in sunny, open habitats, making them god colonizers of disturbed habitats. Ginkos can be identified by their leaves are uniquely fan-shaped leaves, spur shoots, and on the females, pendulous fleshy seeds.

Homestead Elm (Ulmus carpinifolia): The smoothleaf elm is native to Europe, western Asia, and North Africa. It has a pyramidal form and can be 60’ to 90’ tall when mature. Leaves are oval-shaped, with toothed margins. This elm is somewhat resistant to Dutch elm disease, which has killed many native American elms.

Japanese Tree Lilac (Syringa reticulata): Native to northern Japan, this small tree or large shrub thrives in cooler climates. At most, it will grow 30’ tall, and it has dark green, rounded leaves. The tree has white flowers that bloom in the beginning of the summer and gray, shiny bark with visible lenticels (pores for gas exchange).

Japanese Zelkova (Zelkova serrata): This Japanese tree also grows in Taiwan and Eastern China. The tree appears vase-shaped when young, but can grow between 50’ and 70’ tall. Mature specimens lose their juvenle form and become rounded, with a broad crown. Branching starts close to the ground, making the trunk appear short. Young bark is smooth and gray, with prominent lenticels, which are tiny holes to allow for gas exchange. Older bark exfoliates in patches to expose orange inner bark.  The Japanese Zelkova is used for commercial timber in Asia.

Katsura (Cercidiphyllum japonicum): This large tree has grey bark that peels in strips on mature specimens. Leaves are heart-shaped and serrated, and can have red or purple petioles. Autumn foliage is brilliant orange or red, and fallen leaves are said to smell sweet, like cinnamon or ripe apples. The katsura is native to Japan and China.

Littleleaf Linden (Tilia cordata): Native to Europe, this tree resembles its native relative, the basswood tree. Both trees have heart-shaped leaves with asymmetrical bases. The trees usually grow 50’-60’tall, with grey, rather non-distinct furrowed bark and an ovate or gumdrop-shaped crown when mature. Tea made from linden flowers has traditionally been used as anti-inflammatory medicine, and young leaves can be eaten in salads. The linden grows well moist, well-drained soils, but its adaptability and ability to grow on poorer sites with varying pH make it a good street tree.

Morrow’s Honeysuckle (Lonicera morrowii): Morrow’s honeysuckle is native to Asia, and is severely invasive in the United States. It has long been used as an ornamental plant, but has the ability to outcompete native plants by outcompeting them for soil nutrient and water resources, as well as shading seedlings under dense thickets; it may even release chemicals toxic to other plants.  It has sweet flowers that attract pollinators from native plants, and its carbohydrate-rich seeds do not give migrating birds as much energy as native plants’ high-fat seeds do. Birds love honeysuckle seeds, and provide the shrub with an effective means of dispersal. Morrow’s honeysuckle likes sunny edge environments, and is especially worrisome because it has the capacity to invade even difficult areas, like fens and sandy soils. Morrow’s honeysuckle can be identified by its small, egg-shaped leaves that grow opposite from each other on twigs, its white, tubular flowers, and small red, fleshy seeds. Mature shrubs have thin gray bark, often peeling, and are generally disordered in form.

Mugo Pine (Pinus mugo): Mugo pines are dwarf evergreen trees native to the Central and Southern European mountains. They grow as dense, low shrubs, usually les than 20’ tall, although specimens have reached 50’. They have rigid needles grouped in pairs, and gray scaly bark. They are used as an ornamental, and to prevent erosion and avalanches. Traditionally, needles were used to make oil and herbal tea.

Norway Spruce (Picea abies): This spruce, which is native to northern Europe, can be found all over campus. Although it has the characteristic conical spruce growth form, it can be distinguished by the droopy, pendulous twigs at the end of its branches. Needles are stiff and pointy, and cones are narrow and very long (4” – 6”), and start out green but turn brown when mature. This tree thrives in cold climates, acidic soils, and open areas. In this country, it is used as a windbreak and an ornamental planting. In Europe, this tree may be found in pure stands, or along with Scots pine or European beech, and is commercially valuable for the lumber and pulp industries, and its resin has been used to make pitch and turpentine. Here in North America, snowshoe hares have been known to browse on this species; in Europe, red deer like to eat its bark.

Pin Oak (Quercus palustris): The pin oak can grow up to 120’ tall and 5’ in diameter, and usually reaches 60-90’ with a diameter of 2-3’. It thrives in flat lowland areas, and will dominate sites with wet, heavy, poorly-drained soil, like swamps. The wood from these trees is not well suited for construction, since it tends to warp, so it is used for fuel, pulp, and railroad ties.  Pin oak bark starts out smooth and  reddish-gray, but gets darker and grooved with age. Pin oaks can easily be confused with native Quercus rubra, the northern red oak. However, pin oak leaves are more dissected, with thinner, more pointed lobes, and its lower branches are often horizontal or point downward.

River Birch (Betula nigra): The river birch is native to Eastern North America, from Kansas, to Minnesota, to Connecticut, but its range does not naturally extend into Maine. It thrives in moist, frequently flooded habitats,  hence its name. It can grow from 5-‘ to 70’, and mature specimens have an irregular-looking crown. Leaves are diamond-shaped, with toothed edges, and turn yellow in the autumn. River birch bark is striking, especially in juvenile trees. It is silver-red and peels in strips. Older bark turns brown and scaly. This tree makes a beautiful ornamental planting or street tree.

Scots Pine (Pinus sylvestris): The Scots pine is native to the boreal forests of Northern Europe, from Scotland to Russia, and has been widely introduced to the North America, making it the most widely distributed pine in the world. It is a shade-intolerant tree, and must colonize an open habitat. In Scandinavia, fire maintains Scots pine forests by wiping out older individuals to make room for new growth. Undisturbed in their native habiat, Scots pines can live a long time; trees in Sweden have been found to be over 1,000 years old. Scots pines grow between 30’ and 50’ tall, although they may reach 100’ in Europe, and have an irregular branching pattern, or ‘habit,’ similar to that of the native white pine. The Scots pine can be identified by its brown, flaky bark that looks red near the crown and needles that are grouped in pairs.