Ημερολόγιο της/του biying

All those five pictures represent five iconic taxa.
The lichen belongs to fungi.
The raven belongs to birds.
The squirrel belongs to animals.
The bee belongs to insects.
I am not sure what this plant called, but it belongs to plants.

From the picture of the tree with flowers and leaves, it's obviously that it belongs to flowering phenology and leaf phenology, and the second picture is a bare tree.