LARGE SHADE TREES
The large shade trees require a minimum 30' by 30' clear area to grow. They should not be planted within 20' measured horizontally of any overhead utility lines. This year’s program features a great selection of shade trees all suitable for planting in tree lawns (rights-of-way).
Sugar Maples are native to the midwest and eastern United States. ‘Legacy’ is a popular hardy cultivar noted for its oval form. It has thick, dark green leaves that turn orange and red in fall. Planting in full sun will give the most intense fall color. This maple grows best in well-drained soil but is tolerant of higher pH and clay conditions. The sugar maple leaf is the national symbol of Canada.
Glenleven Linden develops an extremely straight trunk with larger leaves, more open branching and a faster growth rate than other Littleleaf lindens. Its inconspicuous white, mid-summer flowers are very fragrant. Lindens are pH adaptable and pollution tolerant but prefer well drained soil. The leaves are heart shaped and dark green, turning to bright yellow in autumn. Lindens generally are very hardy trees once established and they maintain their pyramidal shape.
Western Catalpa is a large tree that grows fairly quickly to an upright, narrow and distinct form that provides interesting winter character. Its large leaves (6 – 12 inches long, 3 – 8 inches wide) are bright green in summer, turning yellow-green to brown but often falling before turning. Its showy, large white flowers appear in May to June followed by seed pods 8 – 12 inches long that persist into fall and winter. It tolerates different soil types and handles alkaline soil and has few insect and disease problems. It is on the list of moderately low water-use trees.
Turkish Filbert or Hazelnut is a popular street tree in Europe with a strong pyramidal form, clean foliage and tolerance to alkaline urban conditions. The leaves are handsome dark green in the summer, sometimes turning yellow to purple in the fall (not consistently). The nuts are ½ - 5/8 inches in diameter and are edible. 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. The first few summers it needs careful watering, but once established, it is quite drought tolerant.
Hackberry is a large rounded tree with widely spread branches and medium to bright green foliage that turns yellow-green in the fall. It is hardy in all areas and in all soils, including difficult alkaline soil conditions. The trunk bark is corky. Some cities are using Hackberries to replace American Elms because they are hardy and relatively disease resistant. The tiny berries of this tree are flavored like dates and relished by birds.
Kentucky Coffeetree is an extremely hardy and drought-tolerant tree in our high alkaline soils. The leaves come out late in spring with new leaves tinged pink to purplish, gradually changing to dark green almost dark bluish green in summer and then yellow in fall. The shade of this tree is filtered because of the open shape and small leaflets. It produces 5-10" brown pods in the fall which hang on in the winter, giving the tree an even more interesting winter appearance. It has no serious disease or insect problems.
Bur Oak is a fine, large specimen tree, also called Mossycup Oak due to its distinctive acorn. These slow growing trees are pyramidal to oval in shape when young and develop a broad crown with stout branches at maturity. The rough dark gray to gray-brown bark becomes deep 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 increases the growth rate, although Bur Oaks are drought tolerant, low water-demand trees, once established.
Chinkapin Oak develops an open, rounded crown at maturity. The leaves are sharply toothed with a lustrous, dark forest green color on the upper side and a white and slightly fuzzy underside in summer. Fall leaf color varies anywhere from orange/yellow to brown. Its acorns are about 1 inch long and are favored by wildlife for their sweet flavor. These oaks prefer a well-drained soil. In the wild they grow on dry limestone outcrops and are considered a moderately low water demand tree. They have no serious pest problems.
Shumard Oak, also known as Southern Red Oak, grows from a pyramidal shape to more spreading as it matures. Although native to creek sides and river bottom ground, it is very adaptable and tolerates drought and high pH soils. It transplants easily and has few insect or disease problems. It is more tolerant of clay soils and marginal sites than the northern red oak. Its leaves usually turn russet red in the fall. The acorn has a shallow cap and the nut is striated with brown-black lines.
London Planetree is a cross between American Sycamore and Oriental Planetree. Planted throughout Europe since the 17th century, it is very tolerant of urban conditions, and withstands high pH conditions. Exclamation is a hybrid developed at the Morton Arboretum in Illinois and has a strong central leader and upright pyramidal shape. Its green summer leaves turn yellow and brown in the fall. Its cream to olive green colored bark makes it a very handsome tree in winter. Planetrees produce a 1” diameter round fruit/seed in October. The London Planetree is less susceptible to anthracnose than the American Sycamore. The ‘Exclamation’ cultivar is considered more tolerant of heat, drought and poor soils than the strait species.
Ornamental trees tend to be shorter and/or narrower than smaller and offered for planting in some cases, under higher utility lines.
Wings Tatarian Maple is a graceful, upright spreading small tree grows into a broad rounded shape. Its cream green flowers in spring are followed by bright red samara (fruit) in July, ¾ to 1 inch long, with almost parallel wings. This cultivar was patented by Fort Collins Nursery from seeds collected from Tatarian Maples in the Cheyenne Wyoming Arboretum chosen for their consistently bright red samaras and bright red fall leaves. Its summer leaves are medium green. Tatarian Maples will tolerate drought and alkaline soils and listed as a moderately low water demand tree, once established.
The Spring Snow Crabapple is a dense upright oval variety of crabapple that is considered sterile, producing fruit rarely, if ever. It blooms between mid-April and mid-May with large fragrant white flowers that last three to four weeks depending on weather. It is only slightly susceptible to fire blight and should be planted in areas with full sunlight.
Hedge Maple is an excellent small tree with a dense oval to rounded outline. The leaves are handsome glossy, stiff leathery dark green in the summer holding late into the fall, sometimes turning a clear "butterfly" yellow, other times freezing and turning light brown. Often the trunk and bark are quite corky. This tree will grow in almost any soil, tolerating dry, alkaline, compacted conditions, including clay soils. It is essentially pest and insect free. The name "Hedge Maple" refers to the tree's tolerance of severe pruning. It is often used as a high hedge in Europe.
Sensation Boxelder is a male clone of a tough native maple species. Because it is seedless it less attractive to box elder bugs, which feed on the flowers of female trees and flock to warm brick houses in the fall. Boxelders will tolerate drought and alkaline soils. This is a smaller xeric shade tree with good red and orange fall color.
Autumn Brilliance Serviceberry is a vase shaped small tree reaching 20-25 feet in height and 10-15’ feet in width. It has white flowers in early spring and a small sweet blue/black fruit in June that birds love. Fall leaf color is usually orange to bright red.
Eastern Redbuds are covered with purplish pink flowers prior to leafing out. The flowers bloom along the stems in April and are perfect reddish purple in bud and open into a rosy pink with a purplish tinge, lasting two to three weeks depending on the weather. The leaves are 3-5” wide and heart shaped. It produces 2-4” long by ½” wide seed pods in October. This is a low branched or multi-stemmed tree which does best in full or filtered shade. Redbuds need a protected planting location in our climate and do well when planted under larger trees. Eastern Redbud is the Oklahoma state tree. In Colorado, it has few insect and disease problems.
American Yellowwood (also known as Kentucky Yellowwood) has a broad rounded crown reaching 25-35' in Colorado with upright spreading branches. It has a very smooth light gray bark and is subject to sunscald and should be trunk wrapped each winter. The leaves open yellowish green, turning bright green in the summer sometimes with an almost bluish tinge and yellow to golden yellow in the fall. It has fragrant pendulous white flowers (similar to Wisteria) that bloom in June heavily every 2 to 3 years followed with a small papery pod. It tolerates high pH as well as acid soils and likes full sun. Prune only in summer as the tree bleeds profusely if pruned in winter or spring. This tree has very few insect problems. It gets its name from the yellow heartwood.
Chanticleer Pear (also known as Cleveland Select Pear) is a thornless, narrow upright-pyramidal tree with a compact form. Native to China and Korea, they are covered with white flowers in the spring and rarely bear a very small fruit. Its glossy green summer foliage turns reddish purple in the fall. Because it hardens off early compared to some other pear cultivars, it may be less susceptible to early freezes and has good fire blight resistance