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Trees


Oklaoma Proven! logo.jpgOklahoma Proven is a plant promotion program coordinated by faculty in the
Department of Horticulture and Landscape Architecture at Oklahoma State University. The goal of the program is to recommend plants well-adapted for use across Oklahoma.

 

 

 

Tree for 2017

Fringetree

Chionanthus cultivars

Chionanthus virginicus is a deciduous, native shrub or small tree with a spreading, rounded habit that typically grows 12-20 feet tall and most often occurs in rich, moist woods and hillsides and moist stream banks. The common name fringetree refers to the slightly fragrant, spring flowers which feature airy, terminal, drooping clusters of fringe-like, creamy white petals. Fringetrees are dioecious (separate male and female plants), but also may have perfect flowers on each plant. Male flowers are showier than female flowers. Plants with perfect or female flowers may give way to clusters of olive-like fruits which ripen to a dark, bluish black in late summer and are a food source for birds and wildlife. Cultivars from the Chinese cousin is also available.

  • Exposure: Full sun or light shade
  • Soil: Tolerates wide variety of soils
  • Hardiness: USDA Zone 5-8
2017 Chionanthus cultivars

 

 

 

Tree for 2016

Escarpment Live Oak

Quercus fusiformis

Escarpment live oak is a smaller version of the coastal live oak (Q. virginiana) growing slowly to 20 to 40 feet high and about as wide with picturesquely gnarled branches and evergreen leaves. Escarpment live oak is native to southern Oklahoma through central and western Texas to northern Mexico, which means it is also more drought and cold tolerant than coastal live oak. Because of its slower growth it is a perfect long-lived shade tree for smaller, urban landscapes. Branches provide excellent nesting sites for birds and small mammals. Acorns are elongated and eaten by wildlife. It is also the larval host of the Hairstreak and Horace’s Duskywing butterflies.

  • Exposure: Full sun or light shade
  • Soil: Alkaline to slightly acid, well-drained soils
  • Hardiness: USDA Zone 6-10

 

 

 

 

Tree for 2015

Hedge Maple

Acer campestre

Hedge maple is a small to medium sized tree slowly growing to 25’ to 35’ high and wide. Because of its small size it is perfect for smaller, urban landscapes and even under utility lines. Hedge maple has beautiful green summer foliage that is free of ailments; fall color is yellow to yellow-green in color. Branches often develop very low to the ground providing excellent cover for wildlife, though it can easily be limbed up if desired. Hedge maple is really not too picky of soils; though it prefers rich, well-drained soil it grows well in compacted and alkaline soils. It also tolerates severe pruning and has often been used as a hedge, even walls, especially in Europe. Hedge maple is one of the tougher maples, which is underutilized in the U.S., has few problems, and is very urban tolerant. Golden leaf and variegated leaf forms are available.

  • Exposure: Full sun or light shade
  • Soil: Tolerates wide variety of soils
  • Hardiness: USDA Zone 5-8

 

 

 

Tree for 2014

Desert-willow cultivars

Chilopsis linearis

Desert-willow is not a willow at all, and prefers dry, well-drained soils, compared to true willows, which grow along streams and ponds; in fact, it will not tolerate heavy, wet soils. Because it likes the hotter, drier climates it is an excellent choice for western Oklahoma. Desert-willow grows as a small tree 15’-30’ high and 10’ to 25’ wide. It is a loose, gangly tree favored for its colorful, funnel-shaped flowers that put on their biggest show in early summer, and then bloom sporadically throughout the rest of summer. Flowers can be white, pink, rose, or lavender with purple markings inside and are sweetly fragrant. Foliage is a rich green in summer with no fall color, falling early to reveal the interesting branching structure. Several cultivars exist. Desert-willow makes a great patio or small specimen tree and attracts hummingbirds and other birds.

  • Exposure: Full sun
  • Soil: Dry, well-drained soils
  • Hardiness: USDA Zone 7-9

 

 

 

Tree for 2013

Winterberry Euonymus

Euonymus bungeanus

Winterberry euonymus is a large shrub to small tree with pendulous branches and light green foliage. Flowers are yellowish-green but not showy. Fruits are pinkish capsules which split open at maturity revealing an orange aril (fleshy seed covering). Fall color can be yellow to orange and red. Bark is green with a rough texture and is also quite attractive. Winterberry grows 15’-24’ high and just about as wide. It is very adaptable and quite drought tolerant. It is mostly resistant to scale insects that are common on other euonymus species. Winterberry makes a great patio or specimen tree.

  • Exposure: Full sun to part shade
  • Soil: Tolerates a wide range of soils
  • Hardiness: USDA Zone 4-7

 

 

 

Tree for 2012

Chinkapin Oak

Quercus muehlenbergii

A native oak growing throughout most of Oklahoma and eastward, chinkapin oak is a rather attractive shade tree that grows 40 to 50 feet high and wide in the landscape. The tree has a nice medium texture in summer and a medium-coarse texture in winter. Bark on stems and trunk develop into irregular blocky scales with age and is quite attractive. Leaves are a glossy, dark yellow-green in summer with varying fall color of yellow to orangish brown to brown. Chinkapin oak is adapted to various soils, even alkaline soils; and is quite drought resistant and tolerant of windswept sites.

  • Exposure: Full sun to part shade
  • Soil: Prefers well-drained soil
  • Hardiness: USDA Zone 5-9

 

 

 

Tree for 2011

American Elm Collection
New Harmony, Princeton, and Valley Forge

Ulmus americana

With the release of improved, disease resistant American elms, they are once again in demand. ‘Valley Forge’, ‘New Harmony’, and ‘Princeton’ are a few of the cultivars available today. ‘Valley Forge’ is upright, arching, broadly vase-shaped with a full, dense canopy. ‘New Harmony’ develops into a broad vase-shaped crown with arching branches terminating in numerous slender, often drooping branchlets. ‘Princeton’ is also vase-shaped. American elms are adapted to a wide variety of soil conditions, tolerate deicing salts, air pollution, drought, and a range of soil pH. They have yellow fall color.

  • Exposure: Full sun to part shade
  • Soil: Prefers well-drained soil
  • Hardiness: USDA Zone 5-9

 

 

 

Tree for 2010

Indian Cherry

Rhamnus caroliniana

Indian Cherry is a small tree (or large, multi-stemmed shrub) to 20’ tall with a rounded to spreading canopy. It is native to the eastern, southeastern US making it more desirable over its European cousins. The foliage is dark, lustrous green all summer turning yellow to orange yellow in the fall. Probably its greatest asset is the colorful fruits that develop late summer/fall turning red and then to black as they mature. These beautiful, sweet fruit also attract several species of birds and can be used to make jams and jellies.

  • Exposure: Full sun to shade
  • Soil: Prefers well-drained soil
  • Hardiness: USDA Zone 5-9

 

 

 

Tree for 2009

Arizona Cypress

Cupressus arizonica

Chionanthus virginicus is a deciduous, native shrub or small tree with a spreading, rounded habit that typically grows 12-20 feet tall and most often occurs in rich, moist woods and hillsides and moist stream banks. The common name fringetree refers to the slightly fragrant, spring flowers which feature airy, terminal, drooping clusters of fringe-like, creamy white petals. Fringetrees are dioecious (separate male and female plants), but also may have perfect flowers on each plant. Male flowers are showier than female flowers. Plants with perfect or female flowers may give way to clusters of olive-like fruits which ripen to a dark, bluish black in late summer and are a food source for birds and wildlife. Cultivars from the Chinese cousin is also available.

  • Exposure: Full sun or light shade
  • Soil: Tolerates wide variety of soils
  • Hardiness: USDA Zone 5-8

 

 

 

Tree for 2008

Bosnian Pine

Pinus heldreichii

Bosnian Pine is a slow-growing evergreen with a dense pyramidal form when young. It has the potential to grow to 70' tall in its native environment but is more likely to reach only 25 to 30' in the landscape. In the Pirin Mountains of Bulgaria there is a 70' tall Bosnian Pine estimated to be over 1300 years old! Young cones are purple and turn brown as they mature and the seed they produce is edible. Bosnian Pine prefers full sun and once established is quite tolerant of high pH soils and drought. It is also disease resistant and can be used in the landscape where an evergreen or pine is desired and space is limited.

  • Exposure: Full sun
  • Soil: Tolerant of dry and high pH soils
  • Hardiness: USDA Zone 6

 

 

 

Tree for 2007

Oklahoma Redbud

Cercis canadensis var. texensis

A cultivar of Oklahoma’s state tree, ‘Oklahoma’ was discovered in the Arbuckle Mountains and was selected for the incredible magenta flowers that cover the tree in early spring. When the flowers fade, heart-shaped leaves emerge with a beautiful glossy sheen. ‘Oklahoma’ Redbud can withstand full sun and their small size (15' – 25' high) makes them perfect for use under utility lines. They tolerate a wide range of conditions but do best on well-drained soils. ‘Oklahoma’ is one of the most beautiful native trees and is perfect for small yards needing a splash of color or grouped together where space allows.

  • Exposure: Full sun to part shade
  • Soil: Well-drained
  • Hardiness: USDA Zone 6

 

 

 

Tree for 2006

‘Prairifire’ Crabapple

Malus 'Prairfire'

Few trees have as much year-round interest as the crabapple and few crabapples are as beautiful and disease resistant as ‘Prairifire’. ‘Prairifire’ starts the spring with a profusion of rose-pink flowers just as the leaves emerge. As summer progresses the leaves turn from purple-red to dark green and red fruit forms that persist well into the winter. The diseases that affect many crabapples don’t phase this tree and its rounded crown, which will not exceed 20' tall, makes it a perfect choice for planting under utility lines or in masses.

  • Exposure: Full sun
  • Soil: Well-drained
  • Hardiness: USDA Zone 4

 

 

 

Tree for 2005

Cedar Elm

Ulmus crassifolia

Cedar elm can thrive in almost any soil type, including the alkaline and heavy soils common in Oklahoma. It is one of the more disease resistant native elms, producing glossy green leaves in early spring that turn a muted yellow in the fall. Its form can vary from upright-oval to broadly horizontal and it generally matures around 60' tall. It can be distinguished from other elms by its rough-textured leaves, corky projections on young stems, and flowers and fruit produced in the fall.

  • Exposure: Full sun
  • Soil: Tolerates a wide range of conditions
  • Hardiness: USDA Zone 6

 

 

 

Tree for 2004

Shantung Maple

Acer truncatum

Shantung Maple is a drought tolerant small to medium-sized tree great for under power lines or in residential landscapes where there isn’t room for a large tree. It grows quickly but typically only to 30' high. The leaves are star-shaped and typically emerge with an attractive purple tinge. This Asian native can have excellent fall color ranging from yellow to orange or red.

  • Exposure: Full
  • Soil: Tolerates a wide range of conditions
  • Hardiness: USDA Zone 4

 

 

 

Tree for 2003

Kentucky Coffee Tree

Gymnocladus dioica

Kentucky Coffee Tree is an Oklahoma native growing to 60 feet tall. It is very heat and drought tolerant and does well on high pH soils. Although it has few branches when young, it matures to a majestic and beautiful tree with large seed pods adding winter interest.

  • Sun Exposure: Full
  • Soil: Tolerates a wide range of conditions including dry and alkaline soils
  • Hardiness: USDA Zone 4

 

 

 

Tree for 2002

Bur Oak

Quercus macrocarpa

Bur Oak is an Oklahoma native that can grow to 60 feet tall, with an even larger spread, and can tolerate drought, heavy soils, and high pH soils. Bur Oak can grow to be a majestic specimen and is an important wildlife species since many animals feed on its large acorns.

  • Sun Exposure: Full
  • Soil: Adapted to alkaline, sandy, and clay soils
  • Hardiness: USDA Zone 3

 

 

 

 

Tree for 2001

Shumard Oak

Quercus shumardii

Shumard Oak is an Oklahoma native plant that can grow to be over 100’ tall in the wild, but reaches 40 – 60’ in the landscape. Shumard Oak produces healthy green foliage even on alkaline soils, tolerates summer heat and drought, and transplants easily.

  • Sun Exposure: Full
  • Soil: Well-drained
  • Hardiness: USDA Zone 4

 

 

 

Tree for 2000

Bald Cypress

Taxodium distichum

This large Oklahoma native will lose its leaves in the fall after turning a russet or coppery-bronze and can easily grow to 70’ high with a 30’ spread. Tolerant of both wet and dry soils, Bald Cypress makes an outstanding specimen, street tree, or pond-side grove.

  • Sun exposure: Full
  • Soil: Well-drained to flood tolerant
  • Hardiness: USDA Zone 4

 

 

 

Tree for 1999

Chinese Pistache

Pistacia chinensis

Chinese pistache reaches a height of 30’ to 45’ with only a slightly smaller spread. Brilliant yellow leaves may grace the tree in autumn. Chinese pistache is a tough tree tolerant of drought, heat, and heavy soils.

  • Sun Exposure: Full
  • Soil: Tolerates a wide range of conditions including dry and alkaline soils
  • Hardiness: USDA Zone 6