The Arnold Arboretum is sponsoring a two session class on Saturday mornings, November 21 and December 5, beginning at 9:30 a.m., with Arborist Kyle Stephens. This class will provide an overview of the information necessary to identify deciduous trees during their dormant season. Looking at specific character combinations, participants will learn to determine the genus and species of several types of trees in the Boston area. The group will begin indoors with a discussion of basic classification techniques and then go outside to the Arboretum grounds to explore maples, oaks, lindens, buckeyes, hickories, hornbeams and as many other trees as time will allow. This class is recommended for the beginner-to-intermediate tree observer. The first class meets at the Dana Greenhouse Classroom. The second class meets at the Hunnewell Building. Dress warmly for spending the morning outdoors. A hand lens may be helpful, but is not necessary. Fee $65 Arboretum member, $75 nonmember. To register, log on to www.arboretum.harvard.edu.