Summer Phlox is the largest of the Phlox spp. in Illinois. This plant is easy to identify because of its leaves, which have conspicuous secondary veins on their upper surface. In other Phlox spp., only the central vein is prominent. A mature specimen of Summer Phlox will have some leaves that easily exceed ½" in width, while the leaves of other Phlox spp. are less than ½" in width. Summer Phlox usually blooms later than other species in this genus, although its blooming period may overlap with Phlox glaberrima (Smooth Phlox) to a limited extent. Another common name for Phlox paniculata is Garden Phlox.