Sunday, June 27, 2010

In praise of buttonbush for river restoration.


Imagine it's March, late in the season for planting rooted seedling trees in the Midwest.  You see hundreds of  #2 pencil-sized twigs, each with a few pitiful roots on one end, laying in the sun on a stream restoration site in suburban St. Louis.  It's oddly hot with air temps in the high 80's.

Seeing this as I supervised the construction of a project I designed, I insisted the contractor overplant.  We put those seedlings in the ground ( in the design you see here, a composite revetment, planting is very easy) not expecting they'd make it.

Most of those pitiful little pencils grew into big shrubs.  They were buttonbush, Cephalanthus occidentalis.  Big USDA site here.

My BS is in forestry and I've seen many thousands of trees go into the ground; buttonbush breaks all the rules.  As a bioengineering plant is seems to survive anything.

For urban bioengineering (using plants in stream management/stabilization) it's a perfect plant.  It tends to get pushed aside by taller woodies in time, but that's OK, it thrives in both very wet and dry conditions, high and low on a streambank, and can tolerate shade.  It has a dense fibrous root system that strengthens bank surfaces.

Most of my experience with buttonbush is in the St. Louis area, where streambanks are pretty welcoming to plants--most are loess-derived, and the creeks are polluted and full of nutrients.

But I've seen this species thrive on fairly dry sites, and also in standing water, which it does in the Cache River wetlands in southern Illinois, notably in "Buttonbush Swamp," which is very precisely named!  And the plant's range is huge; last image is a USDA range map.

We grow a few near our house.  Seeing this one in bloom today (top photo), I was inspired to write this.  I should note that it looks very much like dogwood when not in bloom, with opposite leaves and very similar leaf structure.  I have a hard time telling the young plants apart.

Here's another site on buttonbush.

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