Tom's Blog

Friday, July 23, 2010

Hazel nuts forming

American hazel (Corylus americana), a member of the birch family, is widespread in Wisconsin but not especially common, since it has been crowded out by invasive shrubs. It is a nice "savanna" shrub which forms stunning fall color and has nice nuts that the wildlife love.

Hazel was the only shrub that the original land surveyors in this area recorded, indicating that it was considered desirable, probably because of the edible nuts (sometimes called filberts).

When we were clearing invasive brush at Pleasant Valley Conservancy we always left the hazel, and at present we have quite a bit of it in our open savannas. However, it is fire sensitive, and since we try to burn our savannas every year, most of the shrubs never get very large. However, we have a couple of nice specimens near our cabin which we protect from fire and these are now becoming fairly good sized. The photo shows the ripening nuts of one of these specimens.

Hazel flowers are monoecious. The male flowers (catkins) form in the fall of the year and then go dormant until spring, when they complete their life cycle by forming pollen. The attractive mature hazel catkins are an early sign of spring. As in many shrub species, the female flowers are fairly inconspicuous.

Although hazel is a native species, it is rhizomatous and left to itself can form large clones, especially in open savannas where light is plentiful. This is one reason why we like to burn our savannas every year, since we want to maintain the open character of our savannas.