This is beautiful. :)
I'll give it a more serious shot later, but the Tree Gallery tree looks awesome, great work!
yeah! Phototropism would be great. I plan to do it (even if i didn't know the word, thanks to you), something like the higher it is, the more luminosity there is, and some shadow area to simulate the other trees around, as if we were in a forest. It'll be really interesting and add some constraints in the growth of branches. Thanks!