The summer heat lingers, but hints of autumn can already be seen in the Arboretum and surrounding landscape. I know the seasonal change is coming when I start seeing bits of red on the ground and in trees: the beginning of what will be a spectacular show of fall foliage on poison ivy (Toxicodendron radicans). This ubiquitous creeping/climbing native is one of the first woody vines to show changing leaf color in the autumn, peaking in a blazing display of scarlet, burgundy, gold, and orange. While it is quite ornamental and its small white fruits provide food for many bird species, poison ivy is vilified for its ability to cause itchy rashes on most people who come in contact with it. So admire it from afar, and save your fall foliage fondling for tamer plants like ‘Schlesingeri’ red maple (Acer rubrum ‘Schlesingeri’), whose already bronze-tinted leaves provide another early sign of autumn.
For a complete review of poison ivy, complete with tips for discerning it from other similar-looking plants, read William T. Gillis’s enlightening Arnoldia article [PDF]. Fellow nomenclature nerds will enjoy this quote from the article: “Few topics can steam up a group of taxonomists so much as arguing the merits of Rhus over Toxicodendron as the name of poison ivy and its kin.”