European White Birch (Betula pendula)


European White Birch

(Betula pendula)

A beautiful and graceful specimen mainly prized for its white bark.  The tree starts with a pyramidal habit and becomes more rounded with age attaining heights of 80-100 feet in its native Europe, but rarely exceeds 50-60 feet in the U. S.  They will typically spread 20-35 feet if given enough light and space.

Bark on young trees starts brown and becomes bright white in smooth plates with very little peeling, unlike several of our native species.  Older trees develop a black diamond checked pattern on the lower trunk area and eventually on very old trees, become an unrecognizable deeply ridged black in color.

The leaves are 1-3” long and 1-1 ½” wide with a slender tail.  They are glossy green in the summer with a fair yellow fall color most years, but not as pronounced as our native species.  The almost weeping habit of the branches, look a lot like a weeping willow when the trees mature.

It is best transplanted in the spring and does prefer a moist but well-drained soil.  Hardy from about Maryland to Maine, they have fallen out of favor with many homeowners and horticultural professionals due to their susceptibility to leaf miner and the bronze birch borer.  While treatable with a plant health care program, most people don’t recognize the early signs of damage and wait until it is too late to save the tree.

The showy white bark, pendulous branches, shiny leaves, and even the seeds in their catkin form, prized by many song birds, provide for four seasons of interest.  While not as long lived as some of our natives, the European White Birch is still a handsome specimen deserving some consideration in the landscape. 


Swiss Stone Pine (Pinus cembra)


Swiss Stone Pine

(Pinus cembra)

A native of the Alps and Carpathian Mountains of central Europe, Swiss Stone Pine was introduced to the US as a tough and cold hardy addition to our suburban landscapes. It can attain heights of 80 to 120 feet high by 25-50 feet wide in its native environs, but usually attains a height of 40-60 feet and a width of 20-30 feet in the US.  There are also several dwarf and miniature varieties that mature at lesser sizes, including some used for bonsai.  Swiss Stone Pine is a slow growing species that can live 500-1000 years in its native climate and easily to 100 in the US.  It develops and maintains a dense conical shape when young right through old age.

The needles are in bundles called fascicles in groups of five and are 2.5 to 4 inches long.  They are blue green in color and soft to the touch.  Young candles emerge light green and provide an interesting contrast in spring.  The new needles usually persist for three years before dropping.

Fruits or cones are rounded 1.5-3” in size and appear alone or in clusters turning from green to brown and maturing in three seasons.  The cones are often sliced and used to flavor local schnapps in Europe.  The bark is a dark grayish brown with raised scaly plates as it matures, and can be quite attractive, especially when accented by winter snows. 

Swiss Stone Pine is considered one of the hardiest of the pines able to be grown in sand or clay and tolerate urban, suburban and even drought conditions.  It is a tough tree resistant to most insect and disease problems, including white pine blister rust.

Swiss Stone Pine can be hard to transplant, but once established, it is a cold hardy and low maintenance tree for the landscape.  Providing a moist well drained soil with a sunny location, and good cultural practices of routine pruning to remove dead or diseased tissue, watering the root zone and not the foliage, and leaving fallen needles as a natural mulch is the best way to ensure the best performance from this worthy and attractive conifer.

Maidenhair Tree (Ginkgo biloba)

Maidenhair Tree

(Ginkgo biloba)

The Ginkgo is native to China but is planted in landscapes and streetscapes around the world.  It is one of the oldest trees identified in the fossil record. They are very hardy trees with few insect or disease pests, and are highly tolerant of urban stressors, which is quite uncommon for most gymnosperms.

Ginkgoes are slow growing at first but can achieve heights of more than 100 feet with a spread of 75 feet.  Starting out pyramidal in habit when young they become more rounded and spreading with age.  There are even some columnar varieties like the ‘Sentry’ that will maintain a 25’ spread at maturity.

The bark is a smooth yellow-gray when young, becoming more deeply furrowed and corky with age.   The wood is somewhat soft and brittle and does not have much practical economic value.  The leaves are very unique in the tree world having a fan shape leaf with a V-notch in the center with veins radiating out from the center to the edges.  Medium green to a yellow green in summer, they turn a brilliant yellow in the fall, which unfortunately only lasts for a few days to a week in most cases before dropping off in a massive heap after a good frost or heavy wind.

The plum-like fruits are borne on female plants in the late summer to early fall.  The 1-1.5” fleshy fruit covers a hard nut that is considered a delicacy in some cultures.  The yellow to orange fruit is not edible and smells a bit like the local dog park, but the interior seed can be boiled or roasted and included in many Asian dishes.  Its medicinal value has long been touted and is most often associated with improved memory.  Most towns and landscape contractors specifically plant only male trees to avoid dealing with the future messes encountered with the fruit bearing females.

Overall the Ginkgo is a beautiful and unique specimen tree that can provide multiple seasons of interest with few serious drawbacks.  Given enough space it can be a tough urban tree or great focal point in any garden.




American Sweetgum (Liquidambar styraciflua)

American Sweetgum

(Liquidambar styraciflua)

Native to wet sites on the East Coast, this tree adapts well to lawn and park settings.  It is a medium to fast growing tree and will easily reach 50 to 75 feet or more and nearly as wide.  It is conical in shape when young, turning more rounded in old age.

The leaves are 4to 7 inches long, bright glossy green, and star shaped.  The brilliant fall color is breathtaking in shades of green, yellow, scarlet, orange and purple.

Although Sweetgums will grow in a wide variety of sites, it prefers full sun and moist acidic soil.  They have few serious disease or insect problems, culturally, however, its root system is shallow and wide-spreading, and can cause tripping hazards and damage to infrastructure so allow room for growth when planting.  Also, its fruit, commonly called gumballs or sticky balls, can be a liability.  While fun to play with for most kids, they may pose a tripping hazard in the wrong location.  There is now a fruitless variety of this tree available commercially called ‘Rotundiloba’ which can help alleviate this issue.  In the right location, this is a great native species.

Smooth Sumac (Rhus glabra)


Smooth Sumac

(Rhus glabra)

A small, fast growing native, smooth sumac is an ideal plant for troubled soils.  Native to the Eastern United States, it has been cultivated since 1629 and distributed throughout most of the country since then.  Commonly seen along highways and railroad tracks, it is highly tolerant of poor soils and urban pollution.

Today Smooth Sumac and other members of its genus are finding their way into nurseries and gardens.  They can be used as freestanding trees, large shrubs or for mass plantings and borders.  The fact that they are fast growing and yet stay small is a good selling point.  They are highly invasive, however, and must be monitored.

Flowers emerge in June or July, borne in 6 to 10 inch long greenish-yellow panicles.  Hairy red fruits called drupes form in tight upright clusters where the flowers once were persist until winter.  The fruits can be squeezed to make a pleasantly sour drink, often called “Indian Lemonade”.  Although it actually tastes like a sour apple.  White-tailed deer and flying squirrels are particularly fond of the fruits and when tastier foods have become scarce, many birds turn to them as a backup.  The most attractive feature of this plant is its foliage.  The alternate compound leaves can have from 11 to 31 leaflets and grow up to 2 feet long. Medium green in summer, with whitish smooth undersides, the leaves turn brilliant scarlet, red or orange in autumn.  The early and spectacular show is best in full sun, but this tolerant species can do well just about anywhere.

Tree of Heaven (Ailanthus altissima)

A beautiful name for a tree, often considered a noxious weed. In Victoria, Australia, its cultivation is strictly forbidden. Introduced to the U.S. in 1784 from China, it has since naturalized and has been proclaimed as an invasive species in USDA Hardiness Zones 4 to 10. More tolerant of soot, grime and industrial pollution than almost any other tree, it can grow anywhere in any soil. This can be a problem sometimes when it grows in cracks of sidewalks or parking lots or even dirt filled gutters. Once rooted, the Tree of Heaven will grow 40 to 70 feet tall with a spread of 30 to 50 feet. The rate of growth is extremely fast, especially when young, growing 4 to 6 feet in a single season. They have the ability to come right back after being cut to the ground due to its deep root system. The tree does have some attributes besides its incredible tolerance to abuse. Attractive dark green compound leaves consist of 12 or more leaflets and can be over 2 feet long. The bark is grayish with brown and white vertical streaks extending up the trunk to its open and spreading crown. Yellowish-green flowers appear on both male and female trees in June and turn into the yellow –green samaras on the female plants in July. Samaras may turn to orange-red in August and then persist into winter as a pale brown. The wind-blown seeds then very easily take root the next spring. These trees formerly had no significant pests here in the US, but recently a new invasive called the spotted lantern fly has arrived in the northeast. This extremely aggressive insect primarily feeds on Tree of Heaven, but is not host specific, so when it runs out of its favorite species, it attacks other native trees including fruit trees and grape vines. If you have Tree of Heaven nearby, keep an eye out for this new destructive pest.

Mimosa (Albiza julibrissin)


The Mimosa or Silk-Tree, a native of South Asia, was introduced to North America in 1745, and has adapted well to a wide variety of conditions here in the U.S. It transplants easily and often seeds itself readily, sometimes to the point of being invasive in some areas. It survives a wide range of PH soils and withstands wind and drought. Cold snaps with prolonged periods of weather below freezing, however, will result in injury or death of the plant or parts of it.

Mimosa is a fast grower reaching 20 to 35 feet in height and sometimes wider. It is often multiple stemmed and has a vase shape with a flat top.

The bark is grayish brown and relatively smooth.Both the leaves and flowers have a feathery and tropical look to them adding to their allure in the north. The leaves emerge late in the spring, sometimes causing panic that the tree may have died. The pink bottle-brush like flowers emerge in June or July presenting a unique look in the northeastern U.S.

Crimson King Norway Maple (Acer platanoides)

The Crimson King is the most famous cultivar of the Norway Maples. It is noted for its maroon leaves that last all summer. It was introduced to the United States in 1948 from France.

Commonly planted as a street tree, it is usually intermixed with the green varieties to avoid a dark and somber appearance. The deep colored leaves create a dense shade, making it hard to grow grass or other plants underneath. A shallow surface root system further adds to these difficulties.

Crimson King grows slower and matures at a smaller size than the green-leafed varieties and is more sensitive to some insects and diseases. It tolerates partial shade and a wide range of soils, but it doesn’t like wet feet, so avoid poor drainage areas. At maturity, it will reach 40 feet tall by 50 feet wide, but usually is found smaller.

Avoid excessive pruning to reduce possibility of sun scald, prune in winter and never top! This is a bad practice for all trees as it not only ruins the aesthetic beauty of the tree, but also opens it up to sun scald, diseases and insects. Crimson King maples are highly intolerant of harsh pruning.
When planted in the right location Crimson King maples can be a beautiful and hardy addition to any landscape, providing a little splash of color in your verdant forest.

Flowering Crabapple (Malus sp.)



The leaves are 1 to 2 inches long and are green to reddish green in color.  Fall color can be nice shades of yellow and orange, but it depends on the cultivar.  There are currently over 700 named cultivars and varieties worldwide.  Some are propagated for their flowering, fruiting or fall color, but many are chosen for their disease resistance.

The fruits usually offer better color than the leaves, coming in various hues of yellow, red and orange.  They come as small as 3/8 inches in diameter and as large as 2 inches in diameter.  The crabapples develop in the summer and some persist into winter or until the birds eat them.  They have little crop value to humans, but some can be used to make jellies.

While versatile and attractive, Crabapples can also be high maintenance.  There are several insect problems that can be an issue, but rust, scab and fire blight diseases are usually the more prevalent issues to deal with.  These diseases can be managed with good sanitation, proper spacing, and pruning, as well as fungicide treatments in the early spring.


London Planetree (Platanus x acerifolia)

Aspen 410

A cross between the Oriental Planetree and American Sycamore, the London Planetree was first recorded growing in London in 1663.  It takes its common name from this fact and also that it is the primary street and park tree in London.  London is not alone in its heavy usage of the London Planetree, however.   It is planted by the millions in Zones 4 to 9 in both the northern and southern hemispheres.

London Planes are tough trees that are highly resistant to urban stressors, salt damage and the anthracnose disease that plagues its native cousin the American Sycamore.  They prefer full sun to partial shade and perform best in well drained rich soils, but can tolerate alkaline, moist and even droughty soils.

Highly tolerant of poor soils and pollutants found in urban conditions, the London Planetree is a favorite of cities.  This is also the best place for them as someone else get to clean up after them.  Leaves, twigs and bark are shed all summer and leaves and fruits are shed all fall and winter.

Wide spreading and majestic, 40-60 feet wide, the London Plane will attain heights of 60 to 90 feet.  The branches are smooth and muscular, while the trunk is constantly shedding its flaking bark exposing its olive, cream and brown patches.  Leaves are pale green resembling those of a maple only larger, up to 10 inches across.  The underside of the leaves contain a heavy, choking dust that is loathed by all allergy sufferers.  The spherical fruits, called syncarps, are usually borne in twos, but may come singly or in threes.  Ripening in October and persisting into late winter, they are hardy weapons for children’s games.

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