Norway Maple – EEC Plant of the Month (Not!)

by Ann Farnham, LLA

Norway maple, Acer platanoides

No! Don’t plant this!

This maple tree is seen almost everywhere in the United States north of Hardiness Zone 7 and west to Minnesota. Native to Europe, it has thrived in the U.S.A. since it was introduced in the 18th century to Philadelphia by John Bartram, an early American botanist and horticulturist.

Acer platanoides adapts to extremes in soil (acid or alkaline, clay, sand), compaction, hot and dry weather, air pollution, and either full sun to part shade. As a result, its toughness has contributed to over-use as a street tree (especially after the Elm tree die-out), lawn specimen, and park tree. It has become invasive, crowding out native plants in our woodlands and forests because of its heavy seed crop and high germination rate, and site adaptability. Pests and diseases (Powdery mildew, Verticillium wilt, Anthracnose, Leaf scorch,) have not diminished its spread but the recent arrival of the Asian long-horned beetle may change that for the Norway maple as well as for all the native maples.

Why not?…

Why has the Norway maple fallen out of favor?

  1. It crowds out our native plants, about which we have become more appreciative and knowledgeable.
  2. It is very shallow-rooted, starving other plants of moisture and sunlight, so nothing can grow under its wide canopy (especially lawn grass and most ground covers); the roots also heave sidewalks and streets.
  3. It is fast growing and thereby brittle, causing extensive damage from breakage. Norway maple has been banned in New Hampshire, Maine, and New York.

This Maple is easily confused with our native Sugar Maple, Acer saccharum. They both have opposite, simple, 3 to 5 lobed, dark green, pointed leaves, but the Norway maple leaves are slightly larger, 4 to 7” across as opposed to the 3 to 6” Sugar Maple leaves. The Norway maple has a milky sap which can be extracted from its petioles (the leaf stalk) whereas the Sugar Maple sap is clear. The seeds in both species, samaras, are flattened, two-winged, and differ considerably as can be seen in the photographs.

Norway maple will occasionally reach 90’ in height although 40-50’ high is the average, with a spread 2/3 or equal to the height. It casts very deep shade. The fall foliage is usually yellow and the tree holds its leaves longer than other maples do. The wood is yellowish-white to pale red, and has been used for furniture making although the wood is reportedly not durable.

There are dozens of varieties of Norway maple which include a range of growth habits and leaf color, such as that of ‘Crimson King’ and ‘Dissectum’, which will doubtless continue to make this tree popular. Work is ongoing to develop sterile varieties.

To learn more about invasive plants, go to nps.gov/plants/alien and www.maipic.org

The Ewing Environmental Commission welcomes suggestions for the Plant of the Month from all Ewing residents.

Sourwood – August Tree of the Month

by Ann Farnham, LLA

The tree favored this month by the Ewing Environmental Commission is Sourwood, Oxydendrum arboretum, one of America’s most beautiful native trees. It is at home in the eastern and southeastern United States in USDA Hardiness Zones 5-9. Ewing is located in USDA Zone 6b.

This specimen is located at a residence in the Mountain View neighborhood of Ewing. Sorrel Tree and Lily of the Valley Tree are two other names by which it is known.

Sourwood, a pyramidal, medium-sized deciduous tree (usually 25 to 30’ in height) with slightly drooping branches has glossy green leaves which turn brilliant scarlet in the fall.

Its bell-shaped, fragrant flowers appear in June through July in this area and are white pendulous clusters which persist for several weeks. Honeybees favor the flowers, from which they make a fine flavored honey.

Sourwood is unusual in that it gives us summer flowering as well as extraordinary fall color.

This fine tree prefers an acid, moist and well-drained soil. It will thrive in full sun or partial shade, although the fall color is best when the tree is located in full sun.

 Sourwood attracts few insects or diseases, none of which is serious.

The Ewing Environmental Commission welcomes suggestions for the Tree of the Month from all Ewing residents. Email suggestions or questions to lafarnham@verizon.net.

To calculate the value that trees add to your property, go to treebenefits.com/calculator/

June Tree of the Month – Flowering Dogwood

by  Ann Farnham, LLA

Ewing Township’s Environmental Commission recognizes the beautiful Flowering Dogwood, Cornus Florida, as the Tree of the Month.

This lovely tree, a native to the eastern and central United States, is hardy from USDA zones 5-9 (Ewing is zone 6b), from Massachusetts to Florida and west to Texas.

Among the first trees to bloom in April or May, the Flowering Dogwood becomes covered in greenish-white, bloom-like bracts, four in number, which are usually 3-4” wide.  The bloom period lasts up to two weeks and is followed by clusters of red, berry-like, drupes which turn scarlet in September.  Birds love them.

These trees reach 20-30 feet in height, are beautiful in flower and have outstanding summer and fall foliage.  This species produces brilliant white flowers, but there are varieties ranging from pale pink to warm red.

Flowering Dogwoods do best in acid, well-drained soil, and partial shade, although they will tolerate full sun with appropriate care.  They are, unfortunately, subject to insect and disease problems.  In the Northeast the most widely recognized scourge is a fungus, Anthracnose, which is difficult to control and slowly kills the tree.  Fungicides may be effective.

Dr. Elwin Orton of Rutgers University has developed hybrids of Cornus Florida and Cornus kousa (Japanese dogwood), which are disease resistant and now commercially available.

Some straight species of Flowering Dogwoods which have shown resistance to Anthracnose have been selected and bred and are also now available at nurseries and garden centers.

 The Ewing Environmental Commission (eec@ewingnj.org) welcomes suggestions for the Tree of the Month from all Ewing residents.