Large Shade Trees Flashcards
River Birch
Betula nigra
Plant Description
River Birch is a large (40 to 70 feet tall and slightly narrower in width) and attractive shade tree. It is almost always found in a clump form, although some single-trunk specimens exist. It has an upright and rounded form at maturity, but can be quite narrow when younger. It performs best in moist conditions, such as along stream banks or areas with a high water table, but will also perform well under drier conditions as well. Of all the Birches it is the most suited to hot climates.
The most notable ornamental feature of Betula nigra is the bark, especially when young. Young bark is an attractive cinnamon-brown color with abundant lighter-colored horizontal lenticels. The bark peels away in strips around the trunk or branch, producing a light and papery effect on the tree. Unfortunately this ornamental effect is lost as the tree matures and heavily furrowed bark forms.
The green leaves are 1 1/2 to 3 1/2 inches long, and slightly wider in length, creating a somewhat blunted ovate shape. The margin of the leaf is doubly serrated, though close inspection of the leaf is usually required in order to notice this. In the fall the leaves turn yellow and defoliate in a short time. Somewhat-showy catkins emerge on the tree in the summer and by fall these turn a yellowish-brown.
Landscape Use
Use as a shade tree or as a large ornamental tree and it is popular to use to create a naturalized setting. It is also a useful tree for ecosystem restoration projects in riparian areas.
Points of Interest
While it is considered the most disease-resistant Birch species, it should still be regularly monitored for bronze birch borer.
Notable Cultivars
Cully (Heritage) The most popular cultivar, its bark is lighter than the regular species and can appear as a creamy-tan to white. It is slightly smaller, reaching a maximum of 50 feet. Heritage is also more resistant to the Bronze Birch Bore.
Paper Birch
Betula papyrifera
Plant Description
Paper Birch, also called Canoe or White Birch, is a good replacement selection for Betula pendula because of its similar size, leaf and bark colors and improved resistance to the Bronze Birch Bore. It will reach between 50-70 feet high and about half as wide, producing a good pyramidally-upright form. It is more commonly found in tree form than multi-stem form, and is attractive in both forms. It is more hardy and adaptable than many of the other Birch species.
Young bark on the tree is reddish-brown and glossy. In a few years time the bark turns to a bright, almost pure white. As the name suggests, the white bark peels profusely in what looks likes curled sheets of paper. The underlaying bark has orange tints. As the tree matures, the peeling becomes less-pronounced, and the bark develops black marks on ridges and knot holes in the bark.
The dark green leaves are ovate and 2-4 inches long and elongated, tapering to a sharp point. They are arranged alternately on the stem. The margin of the leaf is doubly-serrated. In the fall the leaves turn a bright and showy yellow color. Catkins are 2-4 inches long and form during the summer. Seed-bearing catkins appear in fall and are 1-2 inches long.
Landscape Use
The very stark and peeling white bark is very ornamental makes this tree best suited for use as an ornamental tree or in small groupings in a naturalized setting.
Points of Interest
Paper Birch should be regularly monitored for Bronze Birch Bore.
Notable Cultivars
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European White Birch
Betula pendula
Plant Description
This is one of nature’s most beautiful trees. The European White Birch has a noble and stately form that is gracefully softened by its gently-weeping form. A mature and healthy specimen is certain to attract plenty of attention in any setting, but it is best used as a focal point where its beauty is truly accented. It grows 40-50 feet high with a spread of about 25-35 feet. The form is pyramidal when young and matures to an upright and rounded form when mature. Plant in a location with moist and cool soil.
Young bark is brown, but as the tree matures it turns to a bright white. A very small amount of peeling will occur on the bark, but the main ornamental feature is the white color and the dark horizontal lenticels. As the tree matures, dark brown or black vertical fissures form on the trunk.
The leafs are dark green and glabrous, and broadly-ovate, almost diamond-shaped and 1-3 inches long. The margin of the leaf is doubly serrated. In the fall the leaves turn a faded yellow, often spotted with brown or black. Long catkins in clusters of three form in the spring and through summer. Shorter seed-bearing catkins appear in late summer and the seeds shed in the fall.
Landscape Use
No matter how it is used, it will be an accent tree. It is a good selection as a shade tree or for use in groves. I have seen it used as a street tree in more temperate and moist climates, but would not recommend it in the intermountain region.
Points of Interest
Unfortunately the European White Birch is highly susceptible to the Bronze Birch Bore and leaf miners. While a healthy tree is normally immune to bores, stressed trees are particularly susceptible.
Notable Cultivars
Dalecarlica The most delicate-looking cultivar of Betula pendula, it has deeply cut leaves that give the tree a very airy look. It is probably the most popular cultivar.
Youngii A dwarf, contorted weeping form. It is a true accent specimen that adds an excellent winter interest with its contorted form.
European Hornbeam
Carpinus betulus
Plant Description
European Hornbeam is a hardy and stately tree that is under utilized in the landscape. It is a large shade tree, reaching 40-60 feet high and 30-40 fee wide. The regular species has a good rounded form, but the most popular forms are columnar or more broadly upright. It is a tough and hardy tree without any significant disease issues.
The bark of the tree is a beautiful smooth slate gray. Very old bark develops an attractive fluted appearance. Unlike most other trees, the bark never develops the rough, corky bark of most other trees.
The dark green leaves are ovate in shape, 2 1/2 to 5 inches long with very visible veins. They are pointed at the tip, but rounded at the base. The margin of the leaf is doubly serrated with very consistent spacing of the serration. Catkins form in the spring but they are not particularly showy. In fall, the fruit appears as pendulous, chain-like clusters.
Landscape Use
The regular species makes an excellent shade or specimen tree. The most commonly occurring forms are columnar and are well suited as a vertical accent next to buildings or lining paths. These columnar forms are also well suited to hedges or wind blocks because of their low branching habit.
Points of Interest
Carpinus betulus is a very long-lived tree, but has a slower growth rate.
Notable Cultivars
Fastigiata The most popular cultivar, it is broadly upright and forms a vase-shape at maturity. It will reach up to 40 feet high and 25 feet wide. It branching habit is very dense and the branches begin very low to the ground.
Pendula A medium sized tree with a strong weeping firm provides a graceful look to this tree.
Eastern Redbud
Cercis canadensis
Plant Description
Cercis canadensis, or Eastern Redbud, is a small to medium sized ornamental tree. It has abroad, oval shape, and can mature to be wider than it is tall (20 to 30 feet tall by 25 to 35 feet wide). It typically branches close to the ground, with only a short main trunk. While not common, it is very beautiful as a multi-stemmed tree. Naturally it is an understory tree, and it will perform best where it has some shade to protect it from the heat of the day.
The bark is a reddish-brown color when young, and then it turns to a dull brown-gray as it matures. The reddish-brown color is visible in cracks and fissures that form on the old bark, creating some minor ornamental interest.
The leaves have a true cordate shape and are 3-5 inches long and wide. Young leaves emerge from the buds a light green color with red highlights on the margin and tip, and then mature to a dark green by summer time. They are arranged oppositely on the stem.
In the spring, before the leaves appear, bright pea-shaped pink blossoms appear prolifically in clusters of 4-8 flowers. Blossoms will often appear on old wood and trunks, as well as on new branches. Following the flowering, 2-3 inch long pea-pod seeds appear on the tree. During the summer the pods are light green, but they turn to a dark brown in the fall. They are often prolific, but are fortunately persistent.
Landscape Use
It is an excellent selection for an ornamental flowering tree. It is best used in a location where it will receive some protection from both the summer sun and winter cold. Irregularly-formed groves of Cercis canadensis are an attractive use of the tree.
Points of Interest
While there are many fine specimens in Cache Valley, it is truly hardy to only zone 5, and some winter kill may occur on the tree during exceptionally cold winters. It is not a particularly long-lived tree, and specimens in the valley probably live even shorter due to being planted in a borderline region for the species hardiness.
Notable Cultivars
Forest Pansy: A purple-leaved variety of Eastern Redbud. The young foliage emerges purple and is very glossy. In our climate the purple color of the leaf is bleached out by the sun and the tree turns a green color by summer.
Covey: A small form of the tree with a strong weeping form and contorted branches. Only reaches 5-7 feet tall.
Alba: A white blooming variety of Eastern Redbud. It shares the same form and size as the regular species.
Ginkgo or Maidenhair Tree
Ginkgo biloba
Plant Description
Ginkgo biloba is a truly unique species, having its own division in the classification system. It is a living fossil, having been on Earth for more than 250 million years. Its long existence can be credited to the remarkable combination of its hardy nature and extreme resistance to disease and insects. If there was ever a trouble-free tree, this is it. It grows slow to 50-80 feet in height, with a spread of 30-40 feet.
The leaves of the Ginkgo are its most unique attribute. They are arranged in whorls which alternate along the stem. There are 3-5 leaves in each whorl. The 2-3 inch long leaf is fan-shaped with a notch at apex of the fan. The leaves turn an attractive bright yellow in fall and drop very quickly. A tree can literally drop all of its leaves within only a couple of days, making it very easy to deal with leaf litter in the fall.
The only drawback to the Ginkgo is the fruit that is produced by female trees. The round fruit can be up to 2 inches in diameter, and is produced in clusters. The flesh of the fruit is messy and has an extremely rancid smell. Only male cultivars of the species should be planted to avoid this problem.
Landscape Use
Ginkgo biloba is an excellent selection for a shade tree or street tree, or as an accent tree in a large landscape. Because it is tolerant of almost any soil condition, it can be planted in the most difficult locations and still be expected to thrive.
Points of Interest
Ginkgo is a dioecious broadleaf conifer.
Notable Cultivars
Autumn Gold: A male selection with a symmetrical and broad pyramidal form. It has good yellow fall color. Grows 50 feet high.
Thornless Common Honeylocust
Gleditsia triacanthos inermis
Plant Description
Gleditsia triacanthos inermis is a hardy and fast growing tree that is able to tolerate a wide range of soil and moisture conditions. At maturity it will reach 50-60 feet tall, with and equal spread. It has a broad and open branching habit, with young branches often exhibiting a zig-zag appearance. The bark is gray-brown in color and develops large furrows when it matures.
Honeylocust leafs out very late in the season, so late in fact that sometimes even I wonder whether the specimen in my yard has died each spring. The leaves are pinnately or bipinnately compound. They are typically 6-8 long, with some individual leaves being much longer, and light green in color. The small leaflets are only 1/3 to 1 1/2 inches long, and are lanceolate in shape. The fine texture of the leaves produces a light shade that permits the planting of annuals or perennials underneath it. The leaflets turn yellow in that fall and drop from the tree followed by the petiole.
In late spring, panicles of greenish-white blossoms appear on the tree. Though they are not visually stimulating, they do have a strong, sweet fragrance. By summertime, large pea-pod seeds (7-8 inches long) begin to form on the tree. In the fall, these turn a dark brown color and will fall from the tree. They can be messy, but fortunately many of the new cultivars produce few seeds.
Landscape Use
Its excellent tolerance of salt and poor soils, as well as its minimal leaf litter, makes it a good choice for a street tree. It makes an attractive shade tree that I would describe as the type of shade that you would like to have a picnic under.
Points of Interest
Never get a Honeylocust that is not thornless, as the thorns are extremely hard and sharp and can grow to be very large. It is susceptible to both wind and snow breakage due to its weak wood.
In many parts of the problem there are serious disease problems impacting Honeylocust populations, including leaf spot, cankers and borers. However, I have not found these diseases to be troublesome in our climate.
Notable Cultivars
Shademaster: The most popular cultivar of Honeylocust it produces a deeper shade than other varieties.
Imperial: A smaller variety (30-35 feet high), it has a very good branching habit and very fine leaves.
Skyline This variety has a more upright growth habit than other varieties, making it more suited for narrow spots or as a street tree. It reaches 40 feet high.
Sunburst A smaller tree than many other Honeylocusts (30-35 feet high), it has a good branching pattern and the new foliage emerges bright yellow before turning a lime green color.
White or Common Mulberry
Morus alba
Plant Description
Common Mulberry is a large (30-50 feet high), fast-growing shade tree with a wild, rounded form and dense canopy. It is considered by many people to be a trash tree because of its tendency to spread and sucker, its weak wood that often leads to breakage, its messy fruit and wild appearance. However, it is extremely tolerant of many soil and climate conditions, making it a suitable selection for more difficult locations.
The bark is light brown and covered with small furrows that give it a fine texture. The leaves are ovate shaped, but many different shapes may appear on the same tree. Some leaves may haves several rounded lobes on the leaf, while others will not. All of the leaves will have a fine serration. The leaves are dark green, and vary widely in size from 2-7 inches long.
The drupe fruit are white, pink or red in color. They are produced prolifically on the tree, and drop in equally prolific amounts. They become very messy, especially around sidewalks, patios or driveways. Birds find the fruit extremely tasty and are regular visitors when the fruit is ripe.
Landscape Use
Dirr describes Morus alba as having essentially no landscape value. However, I have seen plenty of well-formed specimens in Utah. In more moderate climates the Common Mulberry is more likely to become unruly. The biggest problem in our climate is the volunteer seedlings produced by the tree. Use it as a street tree or in difficult conditions.
Points of Interest
Mulberry makes an excellent home for the silk worm and it was originally imported to Europe and American in an attempt to jump-start domestic silk production.
In many parts of the problem there are serious disease problems impacting Honeylocust populations, including leaf spot, cankers and borers. However, I have not found these diseases to be troublesome in our climate.
Notable Cultivars
Chaparral: A small fruitless variety with a weeping form.
Japanese Flowering Cherry
Prunus serrulata
Plant Description
Prunus serrulata is a popular flowering tree in many parts of the nation. There are fewer in Cache Valley because many of the most popular cultivars are marginal for our climate. Flowering cherry is one of the few plants for which people plan vacations around in order to witness their showy blossoms. The species grows to be 50-75 feet tall, but few of the commercial cultivars reach half that size. It naturally has a vase shape with an open, upright branching habit. It has a comparatively short lifespan for a tree, often dying before the tree is 50 years old.
The tree has many ornamental characteristics which contribute to its popularity. The bark is a shiny reddish-brown with prominent horizontal lenticels. In the spring it is at its peak, with medium-sized profuse white or pink blossoms covering the tree. The blossoms are either single or double, depending upon cultivar. The blooms persist for a couple of weeks before tapering off.
The 3-5 inch long leaves are dark green, ovate in shape with a doubly-serrated margin. The leaves are arranged alternately on the stem. In the fall the leaves turn a bronze color or muted red that is quite showy.
Landscape Use
Japanese Flowering Cherry has many different characteristics that make it suited to a wide variety of uses. Its showy flowers and good fall color make it an excellent candidate for an ornamental specimen tree. Its natural vase shape and tolerance of poor soil makes it a good choice for a street tree or parking lot tree. Larger varieties can be used as lawn trees or even small shade trees.
Points of Interest
Prunus serrulata has several pests and problems in our region. It is susceptible to aphids, scale, leaf spot and fireblight. Winter kill can also be a problem with more fragile varieties, causing a significant amount of dieback.
Notable Cultivars
Kwanzan: The most cold hardy of the showy, double blooming cultivars. Its large pink blossoms are extremely showy when in bloom. It grows to 30 feet high and has an excellent vase shape. The fall leaf color is red.
Prunus sargentii - Sargent Cherry Cold hardy to zone 4. Bears single pink blossoms in the spring. Grows 30 feet high and wide and has a good upright branching pattern.
Bur Oak or Mossycup Oak
Quercus macrocarpa
Plant Description
Quercus macrocarpa, or Burr Oak, is an oak species native to the United States. It is one of the most cold tolerant Oaks, hardy to zone 3. It grows to be 50-70 feet tall with a similar or wider spread. It is highly tolerant of poor soils and drought conditions, but can be difficult to establish due to its long tap root that can be damaged during transplanting.
The dark gray-brown bark is very rough with deep furrows and pronounced ridges and tends to flake off. The bark forms quickly on young branches and is a distinctive feature of the tree. The leaves are large (4-10 inches long) and obovate in form. They have several pairs of round lobes that form towards the bottom of the leaf with an otherwise smooth margin. The leaf is dark green and tends to be glabrous, while the underside of the leaf is a pale grey or white color.
1 to 1 1/2 inch acorns form in the summer and ripen in the fall. The acorn is encased half way down the length of the nut or more by the involucre which has a very distinct hairy fringe at its bottom.
Landscape Use
Its size precludes its use in most modern residential landscapes, but it is an excellent choice for a shade tree on commercial or educational campuses.
English Oak
Quercus robur
Plant Description
English Oak is a large shade tree. A full grown oak can only be described as stately. In my opinion it should hold the title of the King of Shade Trees. It is a slow growing tree with strong and sturdy branches, reaching 50-70 feet tall with a similar spread. It has a broad, rounded form, with a good branching pattern that is very attractive during the winter. The canopy grows very dense, producing deep shade beneath the tree.
The bark of the tree is deeply furrowed and ridged, and ornamental in its own right. It has the easily identifiable oak leaf that is obovate in shape with several irregular lobes. The leaf is a glabrous dark green, 2-5 inches long and arranged alternately on the stem. The leaf is smaller than on other oaks, giving the English Oak a finer texture when compared to other oaks. In the fall the leaves either fall while still green or they will turn brown and are often held on the tree into winter.
Inconspicuous catkin flowers emerge in the spring. The fruit consists of small, elongated acorns, 1/2 to 1 inch long. They can be born singly, but often occur in clusters on the tree. They are lime green during the summer, maturing to a rich brown color in the fall.
Landscape Use
Its size limits the situations in which it can be used. It makes an excellent shade tree, though its slow growth rate and large size has made it less popular for use in residential landscapes. It is an excellent tree for use on business or education campuses.
Points of Interest
Dirr is less than enthusiastic about Quercus robur, however it performs well in our climate and other oak species that he recommends do not have the classic oak leaf of the English Oak.
Notable Cultivars
Fastigiata - Skyrocket Oak: A popular columnar form of oak. It is often used along buildings and to line walks or trees. Grows somewhat faster than the regular species. It tends to hold its brown leaves over the winter.
Crimson Spire Identical to Skyrocket except that the fall color is a brilliant red.
Black Locust
Robinia psuedoacacia
Plant Description
Black Locust is a large, deciduous shade tree reaching 40-50 feet tall, with a narrower spread. It is a tree that is both loved and hated; its tough constitution makes it ideal for use in many tough locations, but it suffers from wind and snow breakage and tendency to spread is problematic in most residential and commercial landscapes. Additionally, its 1/2 inch long thorns make it a tree that one wants to keep at arms length, especially while young or low-branched.
Hanging racemes of white blossoms, 4-8 inches long, appear in the late Spring. The flowers are very fragrant, and a tree in full bloom is quite showy. Individual flowers are similar to pea flowers. Flat pea pods form during summer and mature by fall. The 2-4 inch long pods turn brown and hang on the tree into winter.
The odd pinnately compound leaves are true green, and grow to be 6-14 inches long. There are 7-19 leaflets per leaf, each leaflet being elliptic in shape with a smooth margin. In fall the leaves turn a dull yellow and drop.
Landscape Use
Robinia psuedoacacia is a tough and hardy tree that can tolerate nearly any landscape condition. Its tendency to colonize and its wild look make it unattractive for most residential or commercial landscapes though. It is best used in situations such as highway landscaping and reclamation projects.
Points of Interest
Black Locust is susceptible to several different diseases and insects, most troublesome being leaf spots, borders and scale.
Notable Cultivars
Umbraculifera: A fine specimen tree, it only reaches 15-20 feet high and has a dense rounded, umbrella-shaped canopy. It is nearly thornless, but also produces very few flowers.
Purple Robe: One of the most popular and attractive cultivars. It has bright purple blossoms in the spring and blooms for two weeks or longer. The leaves emerge a rusty red in spring before fading to rich green in summer. It is nearly seedless. Grows to 40 feet high.
Twisty Baby (Lacy Lady): A smaller form with heavily contorted branches and stems. The leaves appear to be more pendulous than on the regular species. It does not flower. Reaches 12 feet high and wide.
Japanese Pagoda Tree or Scholar Tree
Sophora japonica
Plant Description
Saphora japonica is a large shade tree that reaches 40 to 50 feet tall with a similar spread. It has a spreading form with an open and upright branching habit. It tends to be a faster grower, but I have not seen as much snow and wind breakage on specimens in the valley as I have seen with other quick-growing trees. It will withstand cold, heat and drought conditions once established, but can be difficult to get established.
The bark on young growth is an drab green color with very noticeable light grey lenticels. Mature bark is light brown and has weaving vertical ridges. The leaves are pinnately compund, 6-10 inches long, and composed of 7 to 17 leaflets. Each glossy leaflet is 1-2 inches long and ovate in shape. The canopy of the tree casts an airy shade similar to that of Gleditsia triacanthosvar. inermis.
Panicles of small, cream colored flowers appear in mid-summer. The flowers are mildly aromatic, but even typically are too far from the ground to be of much appreciation. Following the flowers a 3-8 inch long pear pod forms on the tree and ripens in the fall. The pods appear to be vacuum packed around each individual seed, creating an interesting effect of a string of pearls - though I have heard it described in other, less flattering ways.
Landscape Use
Japanese Pagodatree is underused in the landscape and deserves more attention for use as a shade tree or street tree, especially since it has a high tolerance for urban pollution.
