Which varieties of fringe tree have glossy leaves? I am especially interested in a comparison between C. virginicus and C. retusus.
More than one variety of fringe tree (Chionanthus) is described as having lustrous leaves. According to Michael Dirr’s Dirr’s Hardy Trees and Shrubs (Timber Press, 1997), Chionanthus retusus has “3- to 8-inch long, lustrous dark green leaves,” while C. virginicus has “3- to 8-inch long leaves [which] vary from medium to dark green, with various degrees of gloss.”
If you wish to see images, you can search Google images with the different species names. Oregon State University’s online guide to Landscape Plants has good detailed images and descriptions of these two species of Chionanthus.