Norway maple (Acer platanoides)
SCIENTIFIC SYNONYMS: There are no scientific synonyms for
CONFIRMATION STATUS: Confirmed.
TAXONOMY: The currently accepted scientific name for Norway maple
is Acer platanoides L. Over 100 cultivars of Norway maple have been
developed for commercial trade in North America.
NATIVE STATUS: Introduced, United States and Canada.
GENERAL BOTANICAL CHARACTERISTICS: Norway maple is a
nonnative tree, usually 40 to 98 feet (12-30 m) in height, with widely
spreading, ascending branches. In Europe, Norway maple trees typically
grow to a maximum diameter at breast height of 76 inches (190 cm) and
live to 150 years. Bark on older trees becomes furrowed. Fruits of Norway
maple are 2-winged samaras and each half of the fruit is typically 1.4 to 2.2
inches (3.5-5.5 cm) long.
The biology and ecology of Norway maple are not well-studied in North
America. More research is needed to better understand its key biological
traits, habitat requirements and limitations, and interactions with native
North American flora and fauna.
REGENERATION PROCESSES: Norway maple is dioecious and is
insect pollinated. Norway maple seeds are wind-dispersed. Dispersal
distance from seed source is enhanced by winged samaras. Estimated
lateral distance traveled by samaras in a 6.2 miles/hour (10 km/hr)
breeze when dropped from a height of "approximately 3/4 of the
maximum height of the species" was 165 feet (50.3 m). Norway maple
samaras dry substantially before dispersal and seeds are desiccation-
tolerant thereafter. Seeds are dispersed in fall, which provides a high
likelihood of protection under winter snow, conditions usually sufficient
Seeds germinate in spring, following an obligatory period of cold
stratification at 37 to 40 degrees Fahrenheit (3-4 °C) for 90-120 days.
Germination is apparently enhanced by soil disturbance, although
exposure to mineral soil is not a prerequisite for germination. Norway
maple produces abundant seedlings each spring. First true leaves are
formed approximately 3 weeks after seedling emergence. A review of
European silvicultural literature characterizes Norway maple seedlings as
drought tolerant, but other observations indicate that drought resistance of
seedlings is low during early development stages. Tolerance to extreme
heat or cold is limited during early stages of seedling development.
Information concerning the biology of asexual regeneration in Norway
maple is sparse and conflicting. USDA Natural Resources Conservation
Service Plants Database indicates that at least one cultivar of Norway
maple (Crimson King) has the ability to "resprout," but none have "coppice
potential." However, other research indicates Norway maple, along with
sugar maple and red maple (Acer rubrum), as species that regenerate by
"coppicing" following fire. Postharvest stump sprouting has been
documented, although sprouts originating from saplings and smaller trees
are apparently hardier than those from mature overstory trees. A review of
European data categorizes "tendency to sprouting" for Norway maple as
SITE CHARACTERISTICS: As of this writing, there is very little
published information describing the ecological range of Norway maple
in North America. Because Norway maple is commonly mentioned with
sugar maple in eastern North America, and because of their taxonomic
similarity, it is likely that the two species share a similar ecological range
in this region.
In Europe, Norway maple occurs within a climatic range characterized by
maximum and minimum growing degree days (accumulated temperatures
above 5 °C) of 2600 and 1150, respectively. Within this range, it generally
occurs in lowland areas, wide river valleys, and low mountain habitats.
Norway maple is usually found as individuals or small groups in European
mixed forests, and does not form pure stands over large areas.
Norway maple grows best on moist, "adequately" drained, deep, fertile soils.
It is intolerant of low soil nitrogen conditions and is rare on acidic (pH near
4) soils. Norway maple makes "suboptimum" growth on sandy soils or soils
high in lime or clay content, and does not tolerate high evapotranspiration or
prolonged drought. Conflicting reports assert that it is rare on poorly drained
soils, yet it reportedly can tolerate flooding for up to 4 months.
Northern distribution of Norway maple in North America is probably
limited by cold temperatures. Variation in cold tolerance may be related
to genetic source, since many cultivars of Norway maple have been
developed for this trait. Seedlings can survive temperatures to at least
-12 degrees Fahrenheit (-24 °C), although substantial twig tissue damage
can occur. Insulation provided by early-winter snow may reduce seedling
damage from cold temperatures. Overwintering flower buds may be killed
by prolonged exposure to cold temperatures. In Russia, damage to bud
scales and loss of isolated buds have occurred after exposure for 1 hour
at temperatures between 23 and 27 degrees Fahrenheit (-5 to -3 ºC) and
loss of all buds noted below 23 degrees Fahrenheit (-5º). Open flowers are
more sensitive than buds and may be susceptible to late-season frost.
Exposure to temperatures < 27 degrees Fahrenheit (-3 ºC) for only 15
minutes produced necrosis in the stigma of the style, and 30 minutes of
exposure killed entire flowers.
SUCCESSIONAL STATUS: Norway maple seedlings are characterized
as shade tolerant to very shade tolerant. They are often strong competitors
in closed-canopy forest understories within the species' North American
range. Seedling growth apparently ceases when light levels fall below 3%
of full daylight. Norway maple maintains a continuously recruited
"seedling-bank" of persistent, multi-aged seedlings, given a seed source.
It is likely suppressed Norway maple saplings and seedlings respond
favorably following gap formation. In the absence of stand-level
disturbance, it is also likely that Norway maple could become a
dominant overstory species in eastern deciduous forests where it
is established. Along with American beech (Fagus grandifolia) and
sugar maple, Norway maple is gradually replacing previously dominant
oaks (white oak (Quercus alba), northern red oak (Quercus rubra), and
black oak (Quercus velutina)) in the overstory of a New Jersey piedmont
forest. Norway maple becomes less shade tolerant with age and mature
trees have been characterized as intermediate in shade tolerance. Neverthe-
less, where it becomes the canopy dominant, Norway maple can suppress
regeneration of shade tolerant woody species, including even its own
Researchers have raised several serious questions concerning whether
Norway maple seedlings are equal to those of sugar maple in persistence,
shade tolerance, and response to release, and point out the importance of
these questions in determining competitive interactions between the two
species. Further research is needed to determine impacts of Norway maple
invasion on understory species composition and potential effects on
SEASONAL DEVELOPMENT: Reproductive buds are formed during
summer, overwinter, and open in spring when triggered by warm
temperatures. Flowering dates vary geographically, ranging from late
April to early June in eastern North America. Norway maple typically
sheds its leaves later in the season than most native deciduous species
in the northeastern U.S. and adjacent Canada, presumably because the
growing season is longer in its native European habitat where it evolved.
GENERAL DISTRIBUTION: Norway maple is native to continental
Europe and western Asia. It was introduced to the United States in the
mid- to late 1700s in eastern Pennsylvania. A current, accurate description
of Norway maple distribution in North America is problematic. It is widely
planted throughout much of North America, especially along urban streets
and in yards. In many areas it escapes into surrounding forest and wood-
lands, where it may become invasive. Precise distribution information for
Norway maple is lacking.
Based on floras and other literature, herbarium samples, and confirmed
observations, Norway maple can potentially be found in North America,
growing outside cultivation, in the following areas: from New Brunswick
and Cape Breton Island west to Minnesota and south to Tennessee and
North Carolina. In the West, it is found in British Columbia, Washington,
Idaho, and western Montana.
Actual distribution of escaped or invasive Norway maple may be more or
less broad than the above description. Although not confirmed as such,
these are areas where it is most likely to escape cultivation and potentially
become invasive. The "optimal range" in eastern North America is from
southern New England south to Chesapeake Bay, the piedmont of southern
Virginia and northern North Carolina, and the Appalachians of western
North Carolina, South Carolina, and northern Georgia. This distribution
continues west through the northern 1/3 of Alabama and Mississippi and
the northern 2/3rds of Arkansas to eastern Oklahoma, then north to
southeastern South Dakota and southern Minnesota and Wisconsin.
Northern limits of this distribution are delineated by western and
northern coastal areas of the Great Lakes and the St. Lawrence River.
South of this delineation, inland areas of Maine, eastern Quebec, and the
southern Maritimes, as well as northern Vermont/New Hampshire and the
Adirondacks, are not included in this distribution.
SKY MEADOWS DISRIBUTION:
Tree specimens can be found on trails marked in red.
Appalachian Trail/Old Trail
South Ridge/North Ridge
Rolling Meadows/ Lost Mountain
Norway maple may have a larger distribution range in the park than in-
dicated above. Additional specimens may occur near the entrance to the
park adjacent to Gap Run. This species may be spreading in the lower
reaches of the park
HABITAT TYPES AND PLANT COMMUNITIES: Norway maple is
widely planted throughout much of North America. Because it can produce
large numbers of shade-tolerant seedlings, Norway maple may potentially
be found within a variety of forest habitats and plant communities. It is
perhaps best known for its association with the native sugar maple (Acer
saccharum) in the Northeast.
IMPORTANCE AND USES: There are no reports of the use of Norway
maple by North American wildlife, but sugar maple and red maple are
browsed by white-tailed deer, moose, and snowshoe hares.
Norway maple is a popular landscape and street tree throughout much of
the U.S. It is most common in the East and Midwest and less popular in the
South. Its popularity is due to its rapid growth, wide site tolerances,
attractive autumn foliage, and dense, attractive, shade-providing canopy.
Norway maple is used sparingly as a lumber species in Europe for veneer
and for specialty items such as tool handles, gun stocks and violins.
Impacts of Norway maple on communities and ecosystems in North
America derive from its apparent competitive superiority, especially on
forested sites with a cool, moist, rich, shaded environment. Potential effects
of Norway maple invasion include reduced abundance and diversity of
native species and alteration of forest community structure. Norway maple
negatively impacts sugar maple/American beech forests of the northeastern
United States by dominating the seedling layer and displacing shade tolerant
native species. Norway maple seedlings and saplings appear to be strong
understory competitors beneath native species such as sugar maple.
The impact of invasive Norway maple in forested natural areas is likely to
be closely related to seed source proximity. While Norway maple doesn't
require edge habitat to successfully establish, its spread into previously
uncolonized forest habitats is accelerated where adjacent development
with landscape plantings provides a substantial seed source. Conversely,
large unfragmented forest tracts may become colonized by Norway maple
More research is needed to determine the nature and extent of risk posed
by Norway maple invasion to native plants, plant communities, and
ecosystems throughout North America. For example, Norway maple has
been identified as a threat for invading conifer forests of west-central
Crooked Run Valley