Well, my youth was pretty "stormy", I'd say. I wasn't as calm as collected as now, I was pretty impulsive and adventurous, to put it lightly. At some point I joined a group of bandits who were robbing ponies traveling through the forest, and I helped them by using my lightning summoning ability. One time, we attacked a carriage that we thought contained a treasure, but instead it turned out to be some innocent foals, and I almost killed them with my lightning... At that point, I understood what I was doing was wrong. I left the bandits, and started to walk aimlessly through the forests, unsure what to do with my life. That's when I met my teacher, who made me who I am now.
The Druid Brotherhood was founded in the pre-Celestial era by ponies studying the forces of nature and the means to control them. After that, the new druids were always trained by existing ones, like I do now with Tree Song. Our role is mostly to gather information. For countless years we traveled the forests of Equestria in search for any sings that something was out of the ordinary. Which usually means someone is using magic to do something bad, and we should prevent it. Using magic always leaves traces. Most ponies wouldn't notice them, but a trained druid can detect them. There were many instances during Princess Celestia's reign when my predecessors and I warned her about a villain who was going to attack, which helped her maintain the peace during that thousand years period.
For me it's the old, big and strong trees. I admire them.
Despite my name, I like flowers the most. Even the most common ones like daisies and sow thistles are very beautiful in my eyes.
Druid magic is different from unicorn magic, and earth ponies, due to their connection to the nature, are the most likely to have this kind of skills. There were some pegasus and unicorn druids, but most were earth ponies like us.
The druid abilities depend on their individual talents. Neither I nor Tree Song can shapeshift into animals, but some of the druids in the past were able to do it.