Redwood rainforest has five to 10 times the biomass - that's the sheer weight of living material - of, say, deep tropical rainforest in the Amazon basin.

No one knows exactly when or where the redwood entered the history of life on earth, though it is an ancient kind of tree and has come down to our world as an inheritance out of deep time.

The crown of a supertall redwood has a towering, cloudy, irregular form, and the crowns of the tallest redwoods can sometimes look like the plume of exhaust from a rocket taking off.

The seeds of a redwood are released from cones that are about the size of olives. The heartwood of the tree is a dark, shimmery red in color, like old claret. The wood has a lemony scent and is extremely resistant to rot.

Redwoods have an enormous surface area that extends upward into space because they have a propensity to do something called reiteration. A redwood is a fractal. And as they put out limbs, the limbs burst into small trees, copies of the redwood.

The redwoods you can see in Muir Woods are nothing like the redwood titans that stand in the rainforest valleys of the North Coast, closer to Oregon. These are the dreadnoughts of trees, the blue whales of the plant kingdom.