Trees: The Importance of Diversity

The main drag through our neighborhood is lined with Bradford pear trees and it’s beautiful when in flower. Stinky, like dead fish, but pretty if you can get past the odor. Unfortunately, they are our neighborhood’s harbingers of Spring. The trees were planted approximately 18 years ago and I’m guessing were bought for a song by the developer. They’re common and it’s always concerned me. Even more so now that my neighbor’s gorgeous pear trees in her front garden have succumbed to fire blight and will have to be removed. Their invasive nature has landed them on the Illinois Invasive Plant List. In other words, choose something other than a pear. Ironically, the callery pear (Pyrus calleryana), from which the Bradford originates, was brought over from China in an attempt to thwart fire blight disease. No such luck. So what happens if fire blight strikes the pear trees along the parkway? This…

A barren wasteland. The side streets that feed into the main street through our neighborhood were planted with mostly ash trees and sprinkled in were some honey locust, linden and more pear. When the emerald ash borer found his way into town, guess who’s neighborhood took a hit? Our parkways were decimated. For much of last summer, chainsaws buzzed. Giant tree chippers announced that one after another, ash trees were falling like soldiers in a skirmish line. Despite a discount offered by the village, homeowners have been slow to replace the trees. When money’s tight, a parkway tree isn’t exactly a priority. But the effect of a relatively tree-less neighborhood is profound, leaving one feeling naked, incomplete. The sun becomes too harsh and birds find more hospitable accommodations. Something vital and necessary is missing.

Varying the Canopy

Monocultures, or the cultivation of a single species, invite trouble. Too much of a good thing is bound to fail at some point. Particularly since they lack the genetic diversity to withstand the invasion of pests or disease. If one falls, they all fall. This is when variety becomes the spice of garden life. You’re less likely to suffer great losses when a landscape relies on a menagerie of species to populate the space. I’ve been conscious of this fact since we moved here almost 15 years ago. The builder gave us one tree. You guessed it…a Bradford pear. And they plopped it smack dab in the middle of the front yard. I’ve since moved it to the sideyard and to date have added 14 different deciduous trees to the garden with the hope that if one should fall ill, the others will rally and the loss won’t be as great.

A Succession of Bloom

Sometime in mid- to late February, soft tufts of silver emerge from the branches of pussy willow trees (Salix discolor) in the backyard. Within a matter of weeks, the trees are buzzing with hundreds of honey bees in search of late winter sustenance from the pollen coated flowers, which really don’t look like flowers at all.

The pussy willow trees, which I limbed up to add a sculptural touch, flank a Heritage river birch with beautiful cinnamon colored peeling bark. The trio was planted in the back corner to soak up the water that accumulates in this part of the garden. They do their job exceptionally well. Sometimes too well and the area can become quite dry in July and August for the surrounding perennials.

Flanking each side of our pergola are Centennial Blush star magnolias that I planted in September 2016. I was concerned about them coming through the winter this year and expected a not-so-great bloom with the late frosts and wicked cold temps. But low and behold…

Furry buds gave way to a plethora of fragrant pink streaked flowers.

At about the same time, Elizabeth magnolia starts strutting her stuff in the small garden next to our garage. She was looking a bit anemic last year and I wondered how she’d fare after this winter.

I’m happy to report she’s as beautiful as ever and the buttery yellow flowers have been followed by large, paddle-like leaves.

As the Ice Follies daffodils fade, the Autumn Brilliance serviceberry steps on stage. Delicate white flowers emerge followed by edible fruit that has the robins chasing away the cedar waxwings every spring. I’ve watched them get bombed on the fermented berries and bounce on the fence in a drunken stupor. It’s hilarious!

In addition to its beautiful vase shape, serviceberry leaves turn scarlet in the fall.

But nothing matches the fall color of Little Twist cherry. This diminutive specimen stands at the end of my front entry and is perfect for small spaces.

Tiny pink pendulous flowers on zigzagging branches in spring make it even more appealing. The flowers become a deeper pink as they mature. It’s another honey bee magnet.

For the first time in the history of my garden the Prairie Fire crabapple and the redbud have agreed to share the limelight. Much to my pleasure! The redbud has always been my favorite tree and I laugh as I remember planting it as my neighbor stood over my shoulder in disbelief. At no more than three feet tall, he was doubtful that it would take. We laugh every time his wife remarks about my beautiful redbud. It’s now her favorite too. He finally bought her one for their wedding anniversary this month! Can’t think of a better gift.

Fragrant flowers and deep burgundy foliage make Prairie Fire a standout in the front garden. It’s also been resistant to apple scab in all but the worst years.

The redbud, the spring darling of my garden, I deliberately positioned just outside our west windows so I could see it as I descend the stairs about a million times each day. It makes all those trips hauling laundry up and down almost worthwhile, almost.

The last tree to flower is the Ivory Silk tree lilac. It’s a beacon for red admiral butterflies and gives a light sweet scent. It’s bloom time corresponds perfectly with that of Walker’s Low catmint and the combination is one of my favorites. Honey bees love it too.

In early May I planted two Beijing Gold Peking Lilac trees along the west border of the backyard. The tree is a part of the Chicagoland Grows Plant Introduction Program, a plant breeding partnership among the Morton Arboretum, Chicago Botanic Garden and the Ornamental Growers Association of Northern Illinois. Their goal is to develop and test a variety of trees, shrubs, perennials and grasses for viability in our often challenging midwestern landscape. If you’re looking for a new addition to your garden, I strongly encourage you to visit their site.

Do you have a favorite tree in your garden?