An occasional series on Test Tube is a light-hearted but informative guide to trees, fronted by ecologist Markus Eichhorn.
With the final Harry Potter film about to be released, Markus decided to have fun with trees used in the films.
Markus discussed, among other things, the famous Whomping Willow which appears in some of the films.
In particular, he questioned whether it's truly a willow.
It was all tongue-in-cheek, but like a typical scientist Markus has since delivered me the following analysis (for the true tree enthusiast).
"It appears that there are actually two different 'whomping willows' in the Harry Potter films.
"Both are amalgams of several different trees, though in fairness, freezing frames on the DVDs reveals that they have been dressed with appropriate willow leaves.
"The first one, which Harry crashes into in a flying car (yes, I can suspend disbelief) is almost certainly modelled on a sweet chestnut, and the bark was taken from this tree in Kew: http://www.kew.org/news/kew-chestnut-is-whomping-willow-of-harry-potter-films.htm.
"In the second film, the group fights the tree before getting thrown underneath it.
"From a distance it has silvery bark, more like a beech, and those flailing branches resemble lianas.
"Still, however, the close-up shots suggest that there is actually some willow in there.
"That said, what would a tree of wet ground be doing on a rocky outcrop?"