Piedmont forests

big honking treeJoe and Stephanie led the class to several sites of Piedmont forests in Montgomery County, including one patch that I had never visited. Along the Seneca Creek Greenway Trail, there’s contact between the sedimentary rocks that filled in the Culpeper Basin and the crystalline rocks of the Marburg Schist. That’s an opportunity for groundwater to collect, and therefore you can find some tree species that like their feet wet in this otherwise upland locale. Best example: this humongous Box Elder (Acer negundo), found along the remnants of a hedgerow.

peelyspreadingDown along the Potomac at Riley’s Lock, where that same Seneca Creek has its mouth, is a handsome row of salmon-skinned River Birch (Betula nigra) (left), as well as single trees of Black Walnut (Juglans nigra) (right), soaring into the sky.

We talked about mnemonics and keys for separating the white oak and red oak groups. The acorns of the reds, somewhat like red wines, are more acidic and require some aging underground before they germinate (or become palatable to squirrels). The bristle tip on the leaf of a red oak is not a separate structure, but rather an extension of the leaf vein. Even a red oak-group Willow Oak (Quercus phellos) shows a small bristle tip. White or red, a dry oak leaf takes a long time to decompose; thus, “an oak forest is a noisy forest.”