Getting its name from the sassafras tree root originally responsible for its unique flavour, root beer was an exclusively North American beverage until recently.

BBC: What should I drink in your country?

One morning in September 1940, a boy called Marcel Ravidat was exploring the hills above Montignac when his dog, Robot, uncovered a hole beneath a tree root leading to a cave.

BBC: The perfect trip: Dordogne

The Pingwings were knitted penguin puppets who lived in Firmin's barn while The Pogles lived in a tree-root in a wood.

BBC: Oliver Postgate & Bagpuss

"Before the reorganization, we grew as a tree from one root, " Chen says.

CNN: Hope Takes On the World

D-shaped holes in the bark or new tree shoots emerging at the root zone of your ash trees may be a sign of infestation by the Emerald Ash Borer, an insect native to the Far East that targets ash trees, says Dave Dailey of Birchcrest Tree and Landscape, in Rochester, N.

WSJ: Getting to the Roots of Your Trees' Stress

Mushrooms are an easy-to-spot sign of disease that may indicate root rot and a potentially unstable tree.

WSJ: Getting to the Roots of Your Trees' Stress

Root cuttings have been nurtured in a nursery to provide "clones" of the parent tree.

BBC: Bid to boost 'charismatic' tree