Which tree has smooth gray bark? Sort it by trunk size, shape and leaf

Large trunk, still smooth: the beeches

If a trunk as thick as a barrel is still smooth and gray, it is almost certainly a beech. The Virginia Tech American beech sheet describes bark that is smooth, thin and gray "even on the largest stems", on a tree up to 100 feet (30 m) tall. Leaves are 2½ to 5½ inches long with 11 to 14 pairs of straight veins, and the twigs are slender and zigzag with long, slender buds about ¾ inch long. The Morton Arboretum calls the bark silvery gray, gives buds over 1 inch long and sharply pointed, and notes that dried leaves stay on the tree well into winter, so a smooth gray tree still holding pale brown leaves in January is a strong beech signal.

European beech is planted in American parks and is the common big beech of Britain and Europe. The Woodland Trust's common beech page describes bark that is smooth, thin and grey, often with slight horizontal etchings, oval leaves with a wavy, hairy edge, reddish-brown torpedo-shaped buds with a criss-cross pattern, and trees growing to more than 40 m (130 ft). The beech page separates American and European beech.

Small and fluted: the hornbeams

A small tree with smooth gray bark stretched over a trunk that ripples like flexed muscle is a hornbeam. NC State's American hornbeam profile describes smooth, tight, thin, bluish-gray bark over an irregularly ridged, heavily fluted trunk, which is why it is called musclewood, ironwood or blue beech. It grows 20 to 30 feet (6–9 m) tall in eastern North America, with doubly toothed leaves 2½ to 5 inches long and small ribbed nutlets carried on three-lobed leafy bracts.

European hornbeam is the British and European version. The Woodland Trust's hornbeam page describes pale grey bark with vertical markings, a short, twisted trunk that ridges with age, and leaves smaller and more deeply furrowed than beech, with finely toothed rather than wavy edges. Winter buds are shorter than beech's, slightly curved and pressed to the twig. The beech vs hornbeam page sets the two side by side.

Smooth only while young: maples, tulip tree and hackberry

Many trees are smooth and gray for their first decades, then change. Red maple is the common one: NC State's red maple profile describes young bark as smooth and light gray, while old trunks turn thick, dark gray and break into large plate-like scales separated by vertical ridges. Opposite leaves with three to five lobes and brilliant red, orange or yellow fall color confirm it. Japanese maple stays small, 15 to 25 feet; NC State notes that young stems are green to reddish brown and older branches take on a gray cast. Striped maple, a small tree or large shrub up to 30 feet, is smooth gray-green with prominent white lengthwise stripes when young, according to Virginia Tech.

Tulip tree starts smooth and light gray-green, then develops flat-topped ridges with white furrows in a diamond pattern, per NC State. Hackberry is smooth and gray-brown when young but soon grows corky individual warts, says Virginia Tech, so warts on gray bark settle it.

Smooth gray bark with flowers or berries: yellowwood and holly

American yellowwood is a medium tree, 30 to 45 feet, planted for its hanging white flowers. NC State's yellowwood profile describes smooth gray bark that turns light gray and pebbly on older trunks, compound leaves 8 to 12 inches long with 7 to 9 leaflets, and fragrant white flower clusters up to 12 inches long in late spring. Smooth gray bark plus compound leaves rules out beech and hornbeam at once.

American holly is the evergreen with smooth gray bark. NC State's holly profile describes light gray-white, smooth bark that may be splotched with red or tan lichens or warty, evergreen leaves with long, sharp, evenly spaced spines, and red or orange berry-like fruit on female trees from September through February. It can reach 40 to 60 feet.

In the UK and Europe

In Britain, smooth grey bark on a big tree is beech; on a smaller, twisted, ridged trunk it is hornbeam. The other common smooth grey trunk is rowan: the Woodland Trust's rowan page describes smooth, silvery grey bark on a tree up to 15 m, with alternate pinnate leaves of 5 to 8 pairs of long, oval, toothed leaflets. The rowan page covers its berries and look-alikes. For every other bark type, see the bark identification guide.

Using a photo

Smooth bark gives a photo app little texture to work with, and young trunks of many species look alike. Photograph the bark at chest height, then a leaf or a winter bud if you can reach one. Tree Identifier names a tree from one photo, and American beech, European beech, European hornbeam, red maple, Japanese maple, and tulip tree are in its Collection. It shows no confidence score or alternatives, so check the answer against the trunk size and leaf in the table above, and use the follow-up chat to ask how that species' bark changes with age. For white rather than gray bark, see trees with white bark.