Identifying characteristics:
The Norway maple is an attractive large tree, 40 to 60 feet in height, with
a dense, rounded, symmetrical crown. The leaves
are simple, opposite, 2.5 to 6 inches long and 4 to 7 inches across, with
5 to 7 bristle-tipped lobes. The margins of the lobes are smooth, or with
1 or 2 pairs of sharp, bristle-tipped teeth per lobe. The leaf surface is
smooth, except for tufts of hairs on the lower surface in the vein axils.
The petioles are reddish and 3 to 4 inches long, with a milky sap. The fall
leaves are less attractive than those of the sugar
maple (Acer saccharum), remaining green or turning yellow. The
flowers are petaled and much
larger, more fragrant, and more showy than those of native maples. The yellow-green
flowers are 0.3 inches in diameter and are produced in terminal clusters
just before the leaves emerge in spring. The fruit
is a pair of samaras joined at the base, with flattened seed cases. The
wings are 1.5 to 2 inches long, and are widely diverging (spreading apart
almost horizontally). Seeds ripen and fall from September to October, and
abundant seed crops are produced almost every year. The leaf scars
are V-shaped with 3 bundle scars. The pairs of leaf scars meet, encircling
the twig. The rounded buds are blunt-tipped, with 4 to 6 greenish-purple
or red, fleshy, lustrous bud scales. The grayish-black bark
is furrowed with shallow, narrow ridges forming a regular diamond pattern.
Similar species:
Ecology:
Distribution: This species is native to Continental Europe, from
Norway southwards and is cultivated throughout Iowa.
Habitat: Hardy from zone 3 to 7, the Norway maple is widely planted in Iowa. It tolerates extremes in soil conditions, thriving in calcareous soils, sand and clay. This species adapts well to the nutrient-poor, compacted soils of cities, and tolerates ozone and sulfur dioxide pollution. Like most maples, it is rarely seriously damaged or killed by diseases or insect pests, but is susceptible to wilt, anthracnose, Verticillium wilt, leaf scorch, frost cracks and various minor insect pests. This species and the purple varieties are susceptible to sun scald and to scorching of the leaf margins in dry summers. When planted too deep, it is subject to the development of girdling roots.
Uses:
Horticulture: This species makes a good shade tree in eastern Iowa,
although the native sugar maple
(Acer saccharum) is a much better choice. Because it adapts well
to urban conditions, however, the Norway maple is often planted as a street
tree in eastern North America. The Norway maple withstands the hot, dry
conditions of central and western Iowa better than the cultivated sugar maple (Acer saccharum),
but not as well as the black maple (A.
nigrum). Some landscaping disadvantages to be considered include
the shallow root system, which prevents grass from growing under it, and
the medium growth rate. These trees may reach a considerable size, but shape
and vigor may be maintained by pruning. Cultivars include 'Emerald Queen,'
planted near the Farmhouse. This is a rapid grower, reaching a height of
50 feet and a spread of 40 feet, with ascending branches and bright yellow
fall foliage. It is recommended as one of the best cultivars for urban planting.
Other notable cultivars are 'Crimson King,' with dark reddish-purple leaves
throughout the growing season; and 'Schwedlerii,' a faster grower but whose
leaves emerge dark reddish-purple, and then turn green.
