Besides these circles of scars, there are scars on each side of the stem which were left by the leaves when they fell in the autumn. These leaf-scars differ distinctly in various species and may be round, narrow, triangular, oval, heart-shaped, or horseshoe-shaped according to the species of the tree. They are either flat upon the stem or on a projection, they are sometimes concave and again convex. They may be opposite each other on the stem, as those of the horsechestnut, maples, and ashes, or the arrangement may be alternate, as that of hickories, walnuts and oaks. The places on the stem where the leaf-scars appear are called _nodes_, and the spaces between the nodes are called _internodes_. Occasionally stipule scars are found on the stems,—inconspicuous scars left by stipules, the leaf-like bodies found at the base of leafstalks on some trees,—and sometimes we find the scars of fruit stalks. [Sidenote: Bundle-scars] [Illustration: BUNDLE-SCARS] Bundle-scars are the scars of the little fibres, the vascular bundles which fastened the leaves to the stems in summer. They are found on the leaf-scars and usually take their shape more or less. On the large leaf-scars they can be seen clearly, but on delicate twigs where the leaf-scars are small it is well to use a magnifying glass. [Sidenote: Buds] In our climate the buds of trees are formed in the summer during the season’s growth. The bud at the tip of the stem is called the _terminal_ bud, the buds in the axils of the leaf-scars are called the _axillary_ or _lateral_ buds. Buds contain complete branches in miniature which develop in the spring into a new crop of twigs. By opening a bud in winter the little leaves can be seen and often a cluster of flowers, packed away from the cold in marvellous warm wrappings. As a rule the terminal bud carries on the growth of the tree and the lateral buds furnish the side branches. Flowers are found in both terminal and lateral buds, but sometimes they are enclosed in buds by themselves which open before the leaves come out in the spring, like those of the red maple and American elm,—these are called _flower_ buds. Occasionally we find two or three lateral buds together called _accessory_ buds,—_superposed_, if placed one above another as they are in the butternut; _collateral_, if side by side as in the red maple. When several buds are crowded together one bud usually remains latent. Latent buds are sometimes caught in the growing bark of the tree and remain undeveloped for years, breaking out at length perhaps up and down the sides of the trunk as we see them in “feathered elms.” These abnormal and irregular buds are called _adventitious_ buds. The winter buds of trees may be large or small, they may be slender, flat, oval, pointed or round, hidden or exposed, they may be smooth, downy, sticky, or rough, covered with scales or naked, and they may differ in color from pale yellow to an inky black.