Description of Trees for April 2006
Trees are listed in categories of large/medium and small, and then alphabetically by English name.
Drought Tolerance: All newly transplanted trees require careful watering in all seasons. Our dry winters are very hard on trees. Once established (3-4 years after planting) all trees for 2006 are either low or low-to-moderate water demand trees.
Growth Rates are not given because that can be somewhat site specific, depending on local soil fertility/texture, watering and other factors. Generally, none of the trees offered are “fast growing” because most “fast growers” have soft wood with weaker branches that are more likely to break in early fall and late spring snowstorms.
Bare Root (BR) trees must be planted immediately – roots cannot dry out! Bare roots, dormant upon arrival, cannot be allowed to dry out because the hair roots (the small roots critical to getting nutrients and water from the soil) will die and endanger the tree’s survival. BR trees may seem more vulnerable, but if handled correctly, have as good or better chance of survival than balled & burlapped (B&B) trees. B&B trees lose much more of their root system when dug for transplanting that BR trees.
Height and width of trees are estimated and adjusted for our area, and therefore, may differ from figures given in resource books based on other areas.
Tree wrap (crepe-paper-like or similar wrap) must be used on all newly planted trees. Wrap from the base of the tree to just above the lowest branches. Wrap trees in mid October and remove wrap in early April of the following year. Wrap the first three winters, or until the bark thickens. Tree wrap helps prevent winter sunscald damage to deciduous trees.
For more information call the Colorado State University Extension office in Jefferson County, 303-271-6620, or see related links for their web site.
Large and Medium height trees that should NOT be planted under power lines.
Bur Oak (Quercus macrocarpa) Balled and burlapped, weighing 50-100 lbs.
A fine, large specimen tree, also called Mossycup Oak (from its acorn) inspiring because of its eventual size and hardiness. Bur Oaks reach 60’ in height and width. The pyramidal to oval shape becomes a broad crown with stout branches at maturity. The rough dark gray to gray-brown bark becomes deeply ridged and furrowed. It is believed that the thick bark helped Bur Oak survive the heat of prairie fires. Bur Oaks grow well in various soil types and are very adaptable to city heat and pollutants. Regular watering (don’t drown it!) increases the growth rate, although Bur Oaks are drought tolerant, low water-demand trees, once established. They need a large area for best growth. Bur Oaks have lustrous green leaves in summer that turn yellow-green, yellow, and finally yellow-brown in fall. They have few insect or disease problems.
Cimmaron Green Ash (Fraxinus pennsylvanica “Cimmzam’) Bare Root
This upright, seedless (male) variety of ash will grow to about 50 X 25 feet. It tends to both leaf out in spring and retain leaves in fall a few days later than other ash varieties. Some botanists believe it is actually a variety of white ash or a hybrid of green and white ash. It has dark green leaves that turn orange-red to rust in the fall. This ash prefers a large rooting area in moist, deep, well-drained soil but adapts to drier alkaline soils, where it will grow but more slowly. While moderately drought-tolerant once established, it should not be allowed to become drought-stressed or it will be very prone to ash-lilac borer. Ash sawfly may damage leaves in some years. Male flowers may be infested with mites that cause galls to form on branches, but this does not adversely affect tree health.
English Oak (Quercus robur) Balled and burlapped, 50-100lbs.
English Oaks tolerate a wide range of soils and are listed as moderately low water demand trees. They develop stately broad round-topped crowns with stout spreading branches, reaching a height and width of 45-55 feet in this area. It is the fastest growing oak and is long-lived. English Oak leaves are dark green in summer and brown in the fall, and may hang on into winter. The acorns are quite small.
Hackberry (Celtis occidentalis) Balled and burlapped, 50-100 lbs.
The open appearance of this large rounded tree results from widely spread branches. Medium to bright green foliage turns yellow-green in the fall. It is hardy in all areas and in all soils, including difficult alkaline soil conditions. The bark on a mature tree is corky. It will reach a mature height of 50-60 feet and 30-35 feet in width. Hackberry trees can grow in wet to very dry areas, but do need water to get established. Hackberry is a low water use tree. Some cities plant Hackberries to replace American Elms because they are hardy and disease resistant. The “berries” on this tree are flavored like dates and relished by birds. The leaves can be disfigured by nipple-galls, small bullet-like growths on the underside of the leaves caused by psyllid insects. Galls do not affect the growth or health of the tree.
Skyline Thornless Honeylocust (Gleditsia triacanthos inermis ‘Skyline’) Bare root
One of the very best varieties of thornless honeylocust, Skyline develops a more upright growth habit. Expect it to mature at about 40 X 30 feet. Small dark green leaflets cast a filtered shade that allows grass growth underneath. Some seedpods may develop in years with favorable weather conditions. Skyline leaflets develop a bright golden yellow fall color. It is relatively tolerant of alkaline soils and drought, once established. Subject to trunk cankers when stressed and to spider mites with drought-stressed. There are several insects that can damage the foliage; these usually do not affect tree health adversely.
Turkish Filbert (Corylus colurna) Balled and burlapped, 50-100 lbs.
One of the top street tree selections in Europe, this tree has a pyramidal form, clean foliage and tolerance to alkaline urban conditions. It grows to 40 feet tall and 25 feet wide. The insect-free leaves are handsome dark green in the summer, sometimes turning yellow to purple in the fall (not consistently) and persist late into the fall. The edible nuts are about ½ inch in diameter. Turkish Filberts thrive in hot summers and cold winters and although a loamy well-drained soil is preferable, they tolerate both acid and alkaline soils. When first establishing the tree, do not over-water. It will probably leaf sparsely the first year. Do not assume that more water will help it. The first few summers it needs careful watering, but once established, it is quite drought tolerant.
Small Trees – Good for planting under overhead power lines
Hedge Maple (Acer campestre) Bare root
This excellent small growing tree slowly reaches a height of about 25 feet and equal spread with dense oval to rounded outline. The leaves are handsome – glossy, stiff, leathery dark green in the summer, holding late into the fall, sometimes turning butter yellow, other times freezing and turning light brown. Older trees may exhibit “corky” bark. It will grow in almost any soil, tolerating dry, alkaline clays, compacted conditions, and has few pest insects or diseases. The name “Hedge Maple” refers to the tree’s tolerance of severe pruning. It is often used as a tall hedge in Europe.
Newport Plum (Prunus cerasifera ‘Newport’) Bare root
This hardy ornamental plum reaches 15-20’ in height and equal spread. It has a rounded form with ascending branches. Fragrant whitish-pink blooms emerge along branches, followed by deep purple foliage when grown in full sun. The leaves turn reddish purple in the fall. It is usually fruitless, but when the 1” diameter fruit does develop, it is edible.
Serviceberry ‘Robin Hill’ (Amelanchier ‘Robin Hill’) Balled & burlapped, 50-100 lbs.
This small tree may reach about 25 feet high and 12 feet wide, with an open, upright oval form. It has pink flower buds opening to white flowers in spring. Small red to purple-black fruit in June-July is very attractive to birds, particularly robins. The foliage is medium to dark green, changing to yellow-orange-red in the fall. Tolerant of many soil types; rarely requires pruning. May develop some suckers or shoots low on the trunk. It is considered a low to moderate water demand tree.
Spring Snow Crabapple (Malus ‘Spring Snow’) Bare root
This dense upright oval variety of crabapple will reach a height of about 20 feet and almost equal width. It blooms between mid-April and mid-May with large fragrant white flowers that last tree to four weeks depending on weather. This crabapple is sterile so it does not produce fruit mess around sidewalks and high-use areas in the fall. Its bright green summer foliage turns yellow in the fall. It is susceptible to fireblight and rust. It should be planted in areas with fill sunlight. All crabapples are considered low water demand trees.
Summer Charm Pekin Lilac (Syringa pekinensis ‘DTR 124’) Bare root
This rounded, sturdy, upright small tree reaches 15 feet in height and not quite as wide. Its compact, dense form with ascending branches makes it suitable for small spaces. It has creamy white flowers in late June to early July after the tree has leafed out. It is not as fragrant as the shrub form. Pekin Lilacs are adaptable to many soil types and compaction and will tolerate high pH soils. They prefer well-drained soil and full sun for best flowering. They are listed as moderately low water use trees.
Tatarian Maple (Acer tataricum) Bare root
This close relative of the more common Amur (ginnala) maple has leaves that do not even look like maple leaves . Tatarian maple grows to about 20 feet tall and wide. The greenish-white flowers in May are small but attractive. These are followed by clusters of typical maple fruits (“wings”) that start out green and turn red in August; then they turn brown and often remain on the tree well into winter. Fall color varies and depends on soil and weather conditions, but can be an attractive reddish-orange and yellow. Tatarian maple is more tolerant of dry alkaline soils than its more commonly planted relative Amur (ginnala) maple. It has few, if any insect or disease problems.
*Tree descriptions edited by Robert Cox, CSU Extension Agent, Horticulture, Jefferson County
