The Arnold Arboretum, 125 Arborway in Boston, will again present one of its most popular class offerings on two successive Saturdays, March 5 and 12, from 9 – 12 noon. Learn the basic information necessary to identify deciduous trees during their dormant season. Looking at specific character combinations, you will determine the genus and species of several types of trees in the Boston area.  Class begins indoors with a discussion of basic classification techniques and continues outside to the Arboretum grounds to examine a variety of trees.  This class is recommended for the beginner-to-intermediate tree observer. Dress in layers for both classroom and outdoor learning. A hand lens may be helpful, but is not necessary.    Price to attend is $65 for Arboretum members, $75 for nonmembers.  To register, call 617-384-5277, or email adulted@arnarb.harvard.edu.