Hi all, I'm curious about what seems to be a branching pattern shared by blood vessels, the amazon river and oak trees, among other things. Can anyone point me in the right direction to learn a bit more about this? Here are some examples: - the amazon river<http://www.nasa.gov/centers/goddard/images/content/103371main_amazon-river.gif> - blood vessels<http://www.istockphoto.com/file_thumbview_approve/6303204/2/istockphoto_6303204-blood-vessels.jpg> - lightning<http://www.istockphoto.com/file_thumbview_approve/3506509/2/istockphoto_3506509-lightning.jpg> - an oak tree<http://www.telegraph.co.uk/news/uknews/4697449/Oak-tree-dating-back-250-years-crashes-to-the-ground-in-Devon.html> What I find interesting are the odd details. An oak tree, lightning, and blood vessels, for example, seem to have these odd double-back knotted points. Things that — to me — do not look this this are.. - a winding river<http://www.istockphoto.com/file_thumbview_approve/4280336/2/istockphoto_4280336-meandering-river-cattle-balloon.jpg> - veins in this leaf<http://www.istockphoto.com/file_thumbview_approve/3569643/2/istockphoto_3569643-green-leaf-3.jpg> - a crack in ice<http://www.istockphoto.com/file_thumbview_approve/11913741/2/istockphoto_11913741-ice-texture.jpg> I actually expected a crack in ice to look a lot more like lightning but it's completely different. These also seem to have their own groupings. The grand canyon<http://earthobservatory.nasa.gov/IOTD/view.php?id=6929> looks like frost<http://www.masterfile.com/stock-photography/image/600-02912692/Close-up-of-Frost>, for example. But I'm particularly curious about the blood vessels/amazon pattern. Cheers, Gary