Saturday Science: Trees

For some reason, the evolution of trees has been on my mind a lot lately. Probably because on a visit to the Field Museum, I noticed the ginkgos in one of the islands in the parkway between the museum and Soldier Field: they looked like pines, one central trunk with the branches all radiating off the way the branches of conifers do (usually -- everything about nature is "usually"), so that they form a pyramid shape.

I did a little research and discovered that ginkgos are most closely related to cycads.

I also discovered that, although they make seeds, they don't have flowers, again like conifers. I spent a bit of time last spring observing the conifers planted around Lincoln Park Conservatory, and, yep: they don't have flowers, just little buds that release pollen and little proto-cones that form seeds when the pollen lands on them.

By contrast, the growth habit of most flowering trees (again, usually) is spreading: they want to capture as much light at possible, and any branch may become a secondary trunk.

Just some thoughts. I'll probably work this into a post in Earth: A Biography (which I'm going to get back into soon), but it needs more research.

(Footnote: And I discovered an error in the signage in the Fern Room at the Conservatory, which starts off "A small dinosaur would feel right at home in this room" since it's all ferns, selaginellas, tree ferns -- and cycads. It goes on to state that seeds hadn't evolved yet, which is not the case: seed-bearing plants first appeared about 360 million years ago, long before the dinosaurs; flowers, however, didn't appear until much later, while dinosaurs were running around doing dinosaur things. In fact, cycads are seed-bearing.)