High in the arid mountain forests of eastern California there is a living tree that's older than the pyramids of Giza and the ancient city-state of Babylon — but its location is a secret. The ...

This program originally broadcast on September 14, 2016. The secret life of trees. They talk to each other, says forester Peter Wohlleben. They have families. We’ll sit down with the tree whisperer.

Trees in mind: simple questions with complicated answers -- Keeping track -- How trees became -- Wood -- Trees without flowers: the conifers -- Trees with flowers: magnolias and other primitives -- ...