An average tree looks very different depending on if we view it from far away or close up. It changes again if we choose to look at it as a colour palette. Maybe you decide to study it in separate parts, the leaves, the bark, the growth patterns, the root system.
You could also choose to see how a tree has functioned in a community (as a meeting place), or anecdotally—what stories do the people who live around it have to tell? Who planted it? What sounds are made by the tree? What does the space around the tree look like? What is it made of? How the tree changes visually over the course of a day? A year?