Gary Walton:
Aspen Bark
Gary Walton:
Betula allegheniensis (Yellow Birch) Bark
Gary Walton:
Betula papyrifera (Paper Birch) with lichens and the algae Trentepohlia
Gary Walton:
Big-tooth aspen bark
Gary Walton:
Heart-leaf Birch (Betula cordifolia)
Gary Walton:
Lenticels on black ash trunk
Gary Walton:
Weathered wood of aspen tree
Gary Walton:
White pine resin