Uncommon Trees to Try
Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist
It's easy to find Norway maple, red maple, flowering pear, sweetgum, poplar, or sycamore trees in many local landscapes, in our parks or along the city streets. Many are familiar friends that we know by name, but what about some of the less familiar trees that we don't often find in this area? Let's take a look at a few you might want to consider if you ever run across them in a nursery.
One interesting tree is the Japanese Pagoda Tree, also known as the Scholar Tree (Sophora japonica). This is a distinctive tree and should be considered as a specimen shade tree. It grows to 75 feet tall. It's has a dense upright crown when young, but becomes spreading and broadly rounded as it matures. It has a moderate rate of grow until it reaches the height of 20 to 30 feet and then it grows very slowly.
One of it's best features is its shiny, bright green compound leaves which turn yellow in the fall. While the compound leaves are fairly large... 6 to 10 inches in length... they break apart in the fall and don't need raking. The tree is a good one for providing filtered shade.
Another distinctive feature of the Pagoda Tree is its flowers which form in late summer... long after most other flowering trees. The flowers are wisteria-like hanging clusters of creamy-white, somewhat fragrant blooms. These form 3 to 8 inch pods in the fall.
This tree has few pest and disease problems. Once it becomes established, it's fairly tolerant of heat and drought. The biggest drawback is the yellow staining that may occur from the fallen pods... so don't plant them near a paved surface. They also take about eight to ten years before they flower, however the cultivated variety `Regent' tends to flower after about six years.
While the Amur Corktree (Phellodendron amurense) probably wouldn't be considered as lovely as the Pagoda tree, it is a tough tree. With a medium growth rate, it reaches a height of 30 to 45 feet at maturity with a spread to match. It has few pests and is tolerant of alkaline soil and drought conditions.
The leaves are a glossy green turning a yellow or bronze in the fall. The flowers are an unremarkable yellow-green. The most attractive features of the Corktree are its overall texture and its bark. Its short trunk, twisted limbs, stout twigs, and large compound leaves give it an overall coarse, rugged appearance. As the tree matures the corky bark becomes ridged and furrowed, creating an attractive and interesting pattern. This broad spreading tree should be considered, but only for large lots and park-type areas.
The Katsura Tree (Cercidiphyllum japonicum) should be deemed a great tree on its beautiful fall color alone. It is a tree though that will need more pampering in our area than the other trees mentioned so far. The Katsura tree grows to a mature height of 40 to 60 feet with a medium rate of growth. Its crown is full and dense, changing from a pyramidal form when young to a more spreading form at maturity. However, some trees maintain their upright form into maturity.
The delicate, heart-shaped leaves are the best feature of the tree. They emerge in the spring with a reddish-purple color, changing to a dark blue-green in the summer, and then to an unmatched apricot-orange in the fall.
In other areas this tree does fine in full sun, but in our area it will need some protection from hot sun and dry winds. It can also have problems with sunburn on the bark. It prefers a moist, well-drained soil which is high in organic matter. This tree doesn't like drought and should be watered carefully to avoid water stress in the hot periods of summer. Mulch with an organic mulch, such as compost or shredded bark. Protect the bark of young trees from full sun. It has few pest problems.
If you are looking for a magnificent small tree you might want to weigh the merits of Japanese Stewartia (Stewartia pseudocamellia). Here's a tree that grows from 20 to 40 feet in height at maturity and has a pyramidal to upright-oval shape. As the Latin name implies, the flowers look like little camellias. These white flowers with their gold-orange centers are produced in late summer over a fairly long span.
The leaves are a dark green in the summer turning to various shades of deep red and purple in the fall. The sinewy bark is another desirable feature of the tree. As the tree matures, the bark flakes off in patches creating an interesting pattern of cream and tan.
This tree doesn't seem to have a lot of pest problems, but it also needs pampering in our area. It prefers an acid, moist soil which is high in organic matter. It should be protected from hot sun and wind. Be sure to mulch with organic mulch.
Finally, the Chinese or Lacebark Elm (Ulmus parvifolia)is a good, tough medium-sized tree that will most likely be admired for its unusual bark. Don't confuse this with the weedy Siberian elm (Ulmus pumila) which pops up here and there of its own accord. The true Chinese or Lacebark elm is much different and much better. First of all, it’s resistant to elm leaf beetle and Dutch elm disease. It grows to a height of 40 to 50 feet with a medium to fast rate of growth. The tree is tolerant of alkaline and poor soils. However, it does prefer moist, well-drained soil.
The small leaves are a shiny dark green. The bark is wonderful... a mottled pattern of gray, green, orange, and brown. There are a number of good cultivated varieties available. Depending on the cultivated variety, it develops a graceful rounded crown or an upright spreading form. If you like the vase shape of the American elm, look for `Emerald Vase' an excellent cultivated variety with an upright spreading form. `Emerald Isle' is another excellent variety with a more rounded type of crown. Both are highly resistant to the elm leaf beetle and Dutch elm disease.