Archive for February 25th, 2010

Speckled Alder (aka Tag alder, gray alder or hoary alder) has a wide distribution across the northern hemisphere in Asia, Europe and North America. In the northeast of this continent, the common species is Alnus incana ssp. rugosa (Du Roi).. Alder grows as a tall shrub or a small tree, and prefers stream banks and wet areas with ample sunlight.

At this time of year, alders are made conspicuous by their catkins and cones, left over from summer. The male flowers are long, slim catkins, while the cone-like structures are female. But wait. What is that curly, leafy stuff around the cones?

You will have guessed from the title. Another gall! This is Alder Tongue Gall. Unlike goldenrod galls, which are caused by insects, Alder Tongue Gall is caused by a fungal pathogen (Taphrina alni) that results in a chemically induced distortion of female alder catkins.

The gall emerges from between the outer scales of the female catkin like a flat, elongated flag. Early in the season, the flag is green, but turns brown or black in the fall. The flag remains attached to the pseudocone throughout its existence.

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