by Steve Sheeky, 2012 Native Plant Intern

Walk along some streams in New England and you may notice one kind of tree roughly lining the banks. You may be looking at Alnus incana ssp. rugosa or the speckled Alder. Look more closely and you’ll see the trees line the stream banks. This tree loves the water and thrives where many upland plants will not grow. A. incana ssp. rugosa is called “speckled” due to the spotted pattern on its deep brown, almost coppery bark.

Examine the leaves and you’ll see the leaves have a textured, almost wrinkled appearance. The leaves have serrated edges and are veined with many parallel veins. The speckled alder most commonly has the “rugosa” subspecies label, which translated into English means “wrinkled”.

One of the main reasons the speckled alder holds my interest is because of its ability to fixate nitrogen in the soil. I live in an old mill town, where nutrients have been severely depleted and high levels of manufacturing waste materials (i.e. zinc and lead) have effectively sterilized the soils. The speckled alder, when combined with other sustainable soil reclamation and remediation techniques, could be a strong contender to assist with reintroducing new microbiological flora to these abused soils. In addition, A. incana has a symbiotic relationship with the Frankia fungi which helps to fix nitrogen in the soil.

The Alnus family of trees spans much of North America and is found in other parts of the world. A. incana ssp. rugosa has a range which is all of New England, the eastern half of Canada and the northern tier of the U.S. Midwest. While the alder has had a quiet history here in New England, in Europe a more colorful history exists. In Venice, Italy, wooden pillars were constructed from rugged, moisture resistant trees from Slovenia and Russia. Over time, the timbers mineralized and became stone-like in their strength. What was the tree which was used to save Venice? It was the alder.

Why not consider using the speckled alder in your home landscape? For such an understated tree, it has a fascinating set of characteristics and history which could bring interest to that deserving corner of your garden.

Bibliography:

1. Native Trees, Shrubs, & Vines. Cullina, William.

2. Yes, I Talk to Plants. http://yesitalktoplants.blogspot.com/2012/01/latin-lingo-rugosa.html. Internet. Retrieved 8 July, 2012.

3. Symbiotic N2 fixation of Alnus incana ssp. rugosa in shrub wetlands of the Adirondack Mountains, New York, USA. http://www.esf.edu/hss/hf%20ref%20pdf/oec.126.94.103.pdf. Internet. Retrieved 8 July, 2012.

Image links:

http://www.nrem.iastate.edu/class/for356/images/maps/Alnus_incana_rugosa.jpg

http://calphotos.berkeley.edu/imgs/512x768/0000_0000/0506/1080.jpeg

http://calphotos.berkeley.edu/imgs/512x768/0000_0000/0107/0298.jpeg

http://upload.wikimedia.org/wikipedia/commons/thumb/e/ec/Alnus_incana_rugosa_illustr.png/853px-Alnus_incana_rugosa_illustr.png

Note:  According to the plant database, there are two Alnus incana ssp. rugosa specimens in Garden in the Woods (parcel #234- across from the New England bog, adjacent to the Western Garden, and parcel #241- near the Calla Pool, across from the entrance to the lady’s-slipper path.