SMA Announces 2015 Urban Tree of the Year

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… and it’s one that’s close to our hearts, in the sense that the Tree of the Year (TOY) is none other than the one featured in bloom in our blog’s banner up top, yellowwood (Cladrastis kentukea). What serendipity!

Surrey, BC Urban Forester Emily Hamilton, who attended NY ReLeaf last summer at Hofstra before she relocated to Canada, wrote a column earlier this year in City Trees about yellowwood. Hamilton wrote:

“I would love to stake claim on the discovery of this beautiful street tree candidate, but I am far from the first to recognize its potential. During my attendance at the Municipal Forestry Institute (MFI) at the Arbor Day Foundation headquarters in Nebraska last February, we were all treated to a private tour of the grounds and while touring, a cluster of us found a common appreciation for American yellowwood or virgilia (Cladrastis kentukea). We noted its rising popularity as a street tree in our first-hand experiences from Oregon to Nebraska to Massachusetts.

Mature yellowwood specimen by Emily Hamilton
Mature yellowwood specimen by Emily Hamilton

Yellowwood is in the Fabaceae family with beautifully fragrant white pea-like flowers. This tree may reach up to 50 feet (15 m) in height and almost the same in spread. Yellowwood is relatively pest-free, seems to do very well in urban conditions so long as it gets adequate water, and Michael Dirr says it is pH adaptable up to about 8.2. It is hardy in Zones 4a through 8b and is native to eastern North America, which is a selling point to some, even with our changing climate and the fact of varying urban micro-environments.

Yellowwood foliage by Emily Hamilton
Yellowwood foliage by Emily Hamilton

Pruning for good structure should be performed when the tree is young; otherwise it can tend to develop multiple competing leaders. Pruning is recommended in the summer rather than spring or fall due to its tendency towards excessive sap bleeding or weeping. Cornell’s Urban Horticulture Institute says yellowwood is easy to transplant B&B or under 2-inch (51 mm) caliper bare root.”

Our colleague Brett O’Brien of Columbia, MO, writes of yellowwood:

“A true fan, such as I consider myself to be, is also enthralled by the smooth, elephant-grey to light brown bark of the tree’s trunk as well as the lustrous reddish-brown stems of this medium size tree.

Remarkably adaptable to the mid-Missouri weather and site conditions, yellowwood is a tree which is not particularly rare but in my opinion is certainly not planted in our area nearly enough. It could be that it is not popularized because in open unirrigated turf areas it’s apt to be a little slow; in my experience I have found that in landscape beds or irrigated areas it grows fairly quickly. A favorite yellowwood of mine is located in downtown Columbia on the west side of a red brick building; an unforgiving site where the tree spends the early morning in deep shade and late afternoon in blazing sunlight. Nevertheless, the yellowwood has thrived.

Yellowwood trees admittedly have a maddening branching habit, generally doing fine until the tree is about chest height when multiple leaders and included bark become quite common. Judicious and timely pruning can help, though at a certain point, it is probably reasonable to just accept that good branching structure is not this tree’s strong suite. Yellowwood tree’s other positive attributes clearly outweigh this one idiosyncrasy and I would suggest that the value and benefit this beautiful tree provides makes consideration for planting worthwhile in many urban areas.”

The gorgeous elephantine bark of yellowwood. Photo by Emily Hamilton
The gorgeous elephantine bark of yellowwood. Photo by Emily Hamilton

 

Lovely overall shape and typical problematic branch structure of yellowwood. Photo by Brett O'Brien
Lovely overall shape and typical problematic branch structure of yellowwood. Photo by Brett O’Brien

The SMA recognizes the underutilized and strongly ornamental yellowwood for its service to urban forests and encourages its use when matched appropriately to site and as part of a diverse urban tree inventory.

Iridescent, fuzzy buds of yellowwood. From http://sites.ipfw.edu/native-trees/
Iridescent, fuzzy buds of yellowwood. From http://sites.ipfw.edu/native-trees

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