Hiker's Guide to the Trees, Shrubs, and Woody Vines of Ricketts Glen State Park (PA)

Hiker's Guide to the Trees, Shrubs,
and Woody Vines of Ricketts Glen State Park - Third Edition (Web Version)
Velvet Leaf Gall on Black Birch, Caused by a Mite (Acari: Eriophyidae)

Updated 17 September 2015.