By Jan Cashman
Besides expressing your individuality, there is good reason to plant different kinds of shade trees in your yard, on your block, and in your city. Even on your boulevard, it might be a good idea to plant trees different from the varieties your neighbors have planted. If one variety is overplanted, an insect or disease could attack it and that tree population would be wiped out. Dutch elm disease was one of those diseases, killing most of the elms commonly planted as boulevard trees in the Midwest. In Bozeman a few years ago, the majority of fall gold black ash trees were killed by an aphid-like insect called cottony psyllid.
Here are five good trees that, although you’ve probably heard of all of them, are less commonly planted in Bozeman’s boulevards and yards. All five will grow well here and are susceptible to few insects and diseases:
Majestic oaks are the granddaddy of trees. Bur oak, an oak native to North Dakota and eastern Montana, tolerates drought and poor soil conditions and is the best oak for our area. Oak’s slow growth, hard wood, and long life, makes it a tree that is planted, not only for now, but for the next generations.
Bur oaks can get a small gall on their branches caused by a wasp. At first glance, these galls can be mistaken for acorns. They are noticeable only in the winter when the tree does not have leaves and may weaken the branch but do not kill the oak.
This hardy maple is more tolerant of alkaline soils than most maples, with an upright growth habit that makes it an attractive, though small, boulevard tree. A selection of tatarian maple called ‘Hot Wings’ produces bright red samaras in mid-summer (Samaras are the two-sided seed pods that look a bit like small butterfly wings.) In the fall, tatarian maple’s leaves turn bright yellow and red.
Japanese Tree Lilac
Japanese tree lilac, a small tree growing to 20 to 25 feet, is covered with large, creamy white, wonderfully fragrant flowers in early July after other lilacs have finished blooming. A couple of improved selections of Japanese tree lilac are now on the market—‘Ivory Silk’ is faster growing with a more upright shape. ‘Snowdance’ has more blooms and is sterile, so produces no seedheads.
In the spring, Ohio buckeye, a tree that grows to 25 to 35 feet, has large, yellow-green flowers; then spiny chestnuts appear in the summer, and its leaves turn yellow to orange to red in the fall. Even though it is native to far-away Ohio and surrounding states, Ohio buckeye grows well here, tolerating our alkaline soils and temperature extremes. The name ‘Buckeye’ comes from the nut’s resemblance to a buck deer’s eye.
The stately elm will grow to a large (over 60 feet tall) tree useful for a shade tree or a boulevard planting. Many new selections, resistant to Dutch elm disease, are being released; ‘Princeton’ and ‘Discovery’ are two that show promise. Elms are fast-growing and tolerant of drought and poor, alkaline soils. At this time of the year, elms can be plagued by aphids.
Since the severe and sudden freeze in October of 2009, the Gallatin Valley has lost many trees—green ash, quaking aspen, maples, flowering crabapples, and others. To help keep our city beautiful, the City of Bozeman has issued vouchers to assist homeowners in replacing their boulevard trees. And they have issued a new “Tree Guide” with recommendations for trees that include the commonly planted green ash, maples, lindens, and honeylocust plus other, less-commonly used trees such as birch, hackberry, and laurel leaf willow.
Try planting one of our five shade tree favorites or another ‘different’ tree and celebrate “Tree Diversity”.