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December Walking Tour - Tree Bark
By Michael J. Roll, Research Horticulturist
I have worked on trees for the past 15 years. Flowers, leaves, fruit, and form have always caught my eye. After the leaves fall and all the fruit is gone I stop paying attention. Then last fall I went to a Bonfils-Stanton lecture with Cedric Pollet who travels around the world taking photos of tree bark. I was skeptical, but left the lecture amazed and intrigued by something I look at every day, however never really noticed let alone appreciated.
Take some time and look at the bark on trees. It is really quite amazing. Besides protecting the interior of the tree from insects, hail, snow, cold, etc., bark also transports nutrients through the phloem from the crown to the roots. Some of the more common types of bark seen at Denver Botanic Gardens include scaly bark, fissured and smooth bark, peeling bark (exfoliating), and furrowed cork bark. Notice how unique each bark’s characteristics are. Look at the colors, feel the texture. Are the lenticels (small openings for air exchange) large or insignificant? Enjoy a tree for its bark; you may discover a whole new tree even though you have been looking at it for years.
- Start by walking south of the Bonfils-Stanton Visitor Center along York Street and look for the tanyosho pine (Pinus densiflora ‘Umbraculifera’). The bark is unusually striking reddish-orange and beautiful exfoliating. The tree is also one of our state champion trees registered on the Colorado Tree Coalition Champion Tree Program.
- Proceed to the northeast corner of the gardens in the Sensory Garden and look for the Chinese elm (Ulmus parvifolia) and the curly-leaf mountain mahogany (Cercocarpus ledifolius). Both display strikingly orange-gray, furrowed, cork bark.
- Walk back past the Visitor Center and move south again. Go to the Scripture Garden and you will find several cedar of Lebanon trees (Cedrus libani), one of which is a state champion tree. The bark is scaly in texture and white\gray with orange between the scales.
- Walk along the path heading west and as soon as it turns north look for several paper bark maples (Acer griseum) in June’s PlantAsia, appropriately named for the papery, copper colored peeling bark.
- Walk through PlantAsia and look for two Manchurian cherry trees (Prunus maackii). You can’t miss the smooth, shiny bronze bark.
- Just to the west in the Birds and Bees Garden look for the lacebark pine (Pinus bungeana) and you will know why it is our most photographed bark.
- Continue north to the Dryland Mesa garden and hunt for the alligator juniper (Juniperus deppeana), a state champion tree. The distinctive bark is gray-brown and patterned like an alligator’s back.
- Finally, if you walk to the northwest corner of the Japanese Garden you can’t miss the classic white bark of the European white birch (Betula pendula) with its pronounced, black lenticels.
You can review this tour through our Gardens Navigator website. Be sure to bring your camera next time you come to the Gardens--you won’t regret it.
Photos by Michael J. Roll