There are two species of aspen in North America and both of them live in eastern Iowa. The two are easily distinguished by their leaves. The quaking leaf is often quite round with nearly smooth edges and the bigtooth leaf is more elongate with somewhat jagged edges. 

Field observations, similar to those examples mentioned in my last blog, show that aversive conditioning is pervasive throughout the natural world. Birds and mammals, having large and complex brains, are especially responsive to this type of learning. 

Everyone knows that monarch butterflies are protected from birds to some extent by the toxic chemistry they inherit from caterpillars who preceded them, who in turn, got it from the milkweed plants they ate. 

Back on Dec. 1, 2016, I offered you a story about the historical medicinal aspects of sassafras and its role in the early exploration of the New World by Europeans in “The Strange Tale of Sassafras.”