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Sad about my favorite tree

2007 July 12

By Ken Moore Flora Columnist

One of the childhood memories I hold vividly is the neighbor’s giant mimosa tree, under which I spent many days playing with fragrant silky flowers in summer and twisted little bean pods in the fall. The mimosa, also called silk tree (Albizia julibrissin), remains for me one of the most exotically beautiful of all trees.

And exotic it is. Having been introduced from Asia in the mid-1700s, it has now made itself at home throughout North Carolina and the entire southeast. I’m still trying to get rid of one I set in my yard two decades ago. Similarly, staff of the N. C. Botanical Garden continue to eradicate a persistent population along the Coker Pinetum on Manning Drive.

Magnificent specimens thrive throughout Carrboro and Chapel Hill. I’m not going to insist that you go out and cut down your mimosa right now, but I am being serious about you being aware that those bean pods can spread beyond your yard. Seed distribution is aided by animals and water. That’s why we should be concerned about the big specimen along Morgan Creek below the bridge across from Frank Porter Graham Elementary School on Smith Level Road. That tree has direct seed dispersal into Morgan Creek for future establishment all the way down to Jordan Lake and beyond. And those two magnificent specimens street side and in the parking lot of the Courtyard on West Franklin Street pose a similar threat. Those seeds reach Jordan Lake by being washed down the storm drains into that same Morgan Creek.

Another vigorous exotic expressing itself now along field and woodland edges, as well as in some of our most inhospitable paved urban sites, is the Tree of Heaven, (Ailanthus altissima). This tree was introduced in the late 1700s from Europe, to where it had earlier been imported from China for potential silkworm production.

The intended silkworm industry failed in Europe and America, but that tree has succeeded all too well and is now displacing our native trees and shrubs with little effort. It is easily recognized along the woods’ edges of the northern Calvander approach to Carrboro. In your neighborhood, you can easily spot single specimens or thickets of upright stems with compound leaves – i.e., each leaf is comprised of 10 to 40 smaller leaflets along each leaf rachis. Vigorous clusters of yellow-green winged fruit on the female trees maturing to a striking rusty red and brown in the late summer are eye catching.

Both of these trees are described in the U.S. Forest Service’s “Nonnative Invasive Plants of Southern Forests, A Field Guide for Identification and Control.” I am content, though sad, to continue the effort to rid my wild landscape of the mimosa and I will not allow the Tree of Heaven a foothold on my little property, even though I find it quite dramatic when in fruit. The future and health of our natural forests is in our hands. You will have to decide how responsible you are going to be.

Email Ken Moore at flora@carrborocitizen.com.
Find more Ken Moore Citizen columns at The Annotated Flora

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