Acer platanoides

Norway Maple

(Aceraceae - Maple Family)

Form

• large shade tree
• maturing to 50' tall by 50' wide
• upright oval growth habit in youth, becoming rounded and spreading with age
• medium growth rate

Culture

• full sun to partial sun (partial shade tolerant in youth)
• prefers cool, moist Summers in deep, well-drained, moist soils; tolerates urban stress conditions (including poor soils, heat, drought, and pollution) much better than Sugar Maple (Acer saccharum) or Red Maple (Acer rubrum), but is not tolerant of prolonged high humidity in the southern reaches of its range
• propagated by budding onto seedling understock, rooted stem cuttings, or seeds
• Maple Family; susceptible to several diseases (including Verticillium Wilt and anthracnose) and pests, but especially prone to frost cracks (bark splitting and sap oozing on the south side of the trunk in Winter), which tend to re-open in the same site Winter after Winter
• abundantly available in ball and burlap form, with many cultivars
• Norway Maple is somewhat sensitive to being transplanted in Autumn, and care should be taken to amend the soil, fertilize, water thoroughly, mulch adequately, and avoid Winter salt spray, to enhance survival chances during the first Winter

Foliage

• opposite, with either dark green, deep purple, bronze, or variegated leaves (depending upon cultivar), and casting a deep shade
• five-lobed, with the basal two lobes smaller than the upper three, with all five lobes incised but not serrated
• palmate veination, with blades about 6" long and 6" wide and larger than Sugar Maple (Acer saccharum)
• petioles are expanded at their bases, causing large leaf scars on the stems upon Autumn abscission
• petioles exude a milky sap when removed from the stem or cut
• fall color is often chartreuse and unattractive, but is occasionally a rich golden yellow

Flowers

• globular inflorescences that emerge in April (before the foliage) are yellow-green and give the otherwise barren tree a strikingly bright lime-colored appearance

Fruits

• two samaras (each 2" long) per stalk, with widely divergent (almost 180 degree) prominent wings
• samaras occur in pendulous clusters, as a striking lime color beneath the dark green foliage in Summer (for the species form, but purplish for the purple-foliaged forms), maturing as brown fruits in October

Twigs

• stout and brown, with green or purple large-scaled prominent buds in Winter, depending upon cultivar
• much stouter and less twiggy than other Maples, with much larger buds

Trunk

• light brown to light gray branches, with light gray trunks
• bark lightly fissured in youth, becoming shallowly interlaced with ridges with age, but not deeply fissured nor platy as is typical of other large Maples with age

ID Summary

• large, opposite, very dark green leaves are five-lobed and incised, with petioles that are enlarged at their point of attachment to the stout stems, leaving large leaf scars upon abscission as a chartreuse to golden-yellow fall color, and having the largest Winter buds of any Maple
• samaras are large with very widely divergent wings, lime-green in mid-Summer, and self-sowing if given the opportunity in urban or wild habitats
• bark is shallowly but densely furrowed and grooved at maturity and dark gray, but not platy or scaly as with other Maples

USAGE

Function

• shade tree for the green-foliaged forms
• focal point or specimen tree if it is purple-foliaged or variegated

Texture

• medium-bold texture in foliage and when bare
• thick density in foliage and average density when bare

Assets

• dense Summer shade
• one of two common shade trees (along with European Beech Fagus sylvatica) that has purple-foliaged variants and a variegated variant
• most urban tolerant of the shade Maples for the Eastern and Midwestern United States (but not the Southern United States, where humidity is too high)
• medium-bold texture in Winter
• fairly symmetrical branching

Liabilities

• shallow root system surfaces with age
• prone to frost cracks on south-facing bark in winter
• does not perform well under humid conditions of the Southern United States
• deep shade beneath mature trees often leads to turf die-out
• usually has poor fall color
• somewhat prone to Verticillium wilt or anthracnose diseases
• variegated form may have branches that revert to the green-foliaged character
• self-sows, displacing native trees when allowed to grow

Habitat

• zones 3 to 7
• native to Northern Europe (but naturalized wherever it is allowed to self-sow

SELECTIONS

Alternates

• broadleaf shade trees with non-green Summer foliage (Acer negundo 'Flamingo', Fagus sylvatica 'Riversii', 'Purpurea Pendula', & 'Tricolor', etc.)

Variants

• Acer platanoides 'Crimson King' - brilliant red-purple emerging foliage, slowly changing to deep purple and maintaining this color (i.e., not fading to bronze or dark green as with most other cultivars) throughout the Summer, but turning to an unattractive purple-brown in Autumn; maturing at 45' tall by 45' wide, but with a slower growth rate than the green-foliaged forms
• Acer platanoides 'Emerald Queen' - the most common cultivar among the green-foliaged forms, growing a little more rapidly than the species form, with an oval-rounded growth habit at maturity; to 50' tall by 40' wide, heat and drought tolerant, with yellow fall color

NOTES

Translation

• Acer is the Latin name for Maple.
• platanoides translates as "like Plane Tree", referring to the similiarity of its leaves to the European Plane Tree (Platanus x acerifolia).

Purpose

• Norway Maple is a shade tree that is an alternative among the Maples for more rapid establishment in some urban areas than the more popular Sugar Maple (Acer saccharum) or Red Maple (Acer rubrum), and is also noted for its purple-foliaged cultivars. While Norway Maple does not establish as rapidly as Silver Maple (Acer saccharinum), the latter has weak wood that is prone to storm damage, and has a lack of branching symmetry that most other Maples have.

Summary

• Acer platanoides is a rounded, dense shade tree at maturity that, along with European Beech (Fagus sylvatica), is one of two options for large, long-lived purple-foliaged shade trees, and is the faster growing and more urban tolerant of the two.