Having made comparisons between very dissimilar trees, compare those which are much alike, as the different kinds of maples, of elms, of oaks, of poplars. As your powers of observation become trained, compare the different varieties of the same kind of fruit trees, if there are good orchards in the vicinity. The different varieties of pears afford excellent contrasts. Contrast the Bartlett with the Flemish Beauty, the Kieffer with the Seckel. In apples, compare the Baldwin with the Spy, the King with the Twenty Ounce. The sweet and sour cherries show marked differences in method of branching. Fruit men can tell many varieties apart in winter. How? Two common hickories are shown in Figs. 203 and 204. How do they differ? Do they differ in length of trunk? General method of branching? Direction of branches? Character of twig growth? Straightness or crookedness of branches? Contrast the slippery elm (Fig. 205) and the common or American elm (Fig. 211). The former has a crotchy or forked growth, and long, stiff, wide-spreading branches. The latter is more vase-like in shape. The branches are willowy and graceful, with a tendency to weep. Compare the oaks. The white and scarlet oaks have short trunks when they grow in fields, and the main branches are comparatively few and make bold angles and curves. The swamp white oak (Fig. 206), however, has a more continuous trunk, with many comparatively small, horizontal, and tortuous branches. [Illustration: _Fig. 206. Swamp White Oak._] With Fig. 206 compare the pepperidge (Fig. 207). This is one of the most unusual and interesting of all our native trees. It grows in swales. It has a very tough-grained wood. The autumn foliage is deep red and handsome. The peculiarities of the tree are the continuation of the trunk to near the summit, and the many lateral, short, deflected, tortuous branches. Consider the structure of the sassafras in Fig. 208. The great branches stand off nearly at right angles to the trunk, and are bushy and twiggy at the ends. Each large branch if cut off at its base and stood upright would look like an independent tree, so tree-like are its branches. Observe how much more bushy the sassafras is than any of the other trees already figured. Compare it in the method of branching and the twigginess with the slippery elm (Fig. 205). [Illustration: _Fig. 207. Pepperidge or Sour Gum. The oddest of New York trees._] But there is still greater brushiness in the thorn-apple (Fig. 209). In twigginess Figs. 208 and 209 are very unlike, however. Pick out the differences. Observe the very short and spur-like twigs in the thorn-apple; also notice how soon the trunk is lost in the branches.