Punctelia rudecta (Ach) Krog is a common blue-green foliose lichen found on hardwood trees and bark in eastern North America (Fig 1, 2). This species is easily identified by the light underside of the thallus, the relatively large lobes at the edges of the colony, and the small white pores present on the top of the thallus that are distinctive of the genus (Fig. 3, 4). Like many lichens, P. rudecta can be used as an indicator species for pollution levels in an environment. This species has been described as pollution-tolerant, but has also been shown to be a reasonable indicator species of vehicle pollution levels (https://www.amnh.org/learn-teach/young-naturalist-awards/winning-essays2/2007-winning-essays/lichens-as-indicators-of-vehicle-pollution).