As a duck who accidentally mutated himself into a plant duck in hopes of furthering his experiments to help solve world hunger, he is an angry villain who lashes at the world the way it lashed back at him.
Before his mutation, Dr. Reginald Bushroot was an aspiring scientist who focused solely on experimentations on plants, hoping to solve world hunger by allowing humans to photosynthesize under sunlight. He was constantly bullied and belittled by his coworkers, however, and the only person who seemed to care about him was his crush, Dr. Rhoda Dendron. When his funding to solve world hunger was about to be cut, he turned to testing the experiment on himself in his greenhouse as a desperate attempt to prove his research was a breakthrough. However, something went wrong, and he was mutated into a plant-like creature with purple foliage as hair. Not realising this, he headed towards the university he worked at to show his results, only to be made fun of, and left in disgrace.
He soon started to learn that he possessed certain powers that allowed him to control the plant kingdom. It made him excited and he wanted to show his findings at the university, only to be brought down by the thought that everyone would just laugh at him or make fun of him again. Unless there was a little accident…
Thus began his first step into villainy. While his colleagues worked late at night on the research that the Dean approved, he attacked them with vines and strangled them to death, their bodies found the next morning covered in vines, which alerted the attention of Darkwing Duck and Launchpad McQuack.
He eventually overheard a conversation between him and Rhoda Dendron, and misinterpreted her worries over him as affection, and had her kidnapped. At that point, he had become very good at using his powers, and easily had the hero and his sidekick cornered with a giant flytrap, whom he would later name Spike.
He then began to mutate Rhoda Dendron the same way he mutated himself, deaf to her pleas and begging. He was eventually mowed down by a lawn mower when he tried to attack Darkwing, who showed up in a nick of time to rescue her. However, it was shown that the plant mutant had regenerative abilities, and was able to regrow himself from a cabbage.
Since then, he had been causing crimes as he no longer could get a job and yet, he needed the money or experimental formula to help his plants, or create a mate or companion so he would no longer be lonely. It was unclear how he had joined the Fearsome Five in later episodes, but it was shown that around them, he is more aggressive and cruel.
Eventually, the Fearsome Five disbanded, and he returned to his more harmless crimes, which were continued to be focused on creating a friend through experiments or helping his plant companions.
He would start to redeem himself as he willingly freed an accidentally mutated Gosalyn when Darkwing wanted her back, and the hero let him escape with a warning.
Bushroot is driven by desire for love and companionship. He had a very low self esteem before his mutation, and this often drags him down from being able to achieve his dreams and goals. Now, after his mutation, it had made things worse. No matter what he does, people would run from him in fright, or attack him on sight. An example could be shown be It's a Wonderful Leaf, where he was just doing some normal shopping, until he was hurt and attacked by the mall shoppers when his disguise fell apart. Part of his villainy appears to be influenced by the citizens' hostility towards him.
Unlike most St Canardians, Bushroot is not aggressive, and all he used to want was world peace. Even as a villain, he has reservations about hurting people except when angered, and most of his crimes revolve around making a wife for himself, or a friend, or feeding his plant friends. This also makes him a coward and a pushover. He was unable to stand up for himself, especially against the bullies in St Canard University, and even now, he still allows himself to be pushed around by his team.
He also has the ability to do good, even after being labelled as a villain. In Twin Beaks, he assisted an army of cow aliens to spy on some evil cabbages, and even helped stop them from wold domination by working together with Darkwing. He also decided to help Darkwing and release Gosalyn when she turned into a slime monster in Slime Okay, You're Okay, where it was revealed he wished to establish a friendship with the hero.
Bushroot is also shown as patient and unconditional. In Night of the Living Spud, he was willing to marry an unpleasant, barely sentient and demanding potato vampire, and even feel sadness and anger for her death. He also took care of a ravenous and savage piece of hedge in Slime Okay, You're Okay, refusing to give up on it even when it caused more trouble than he could handle.
However, this does not mean Bushroot is not a good person. Due to his selfishness and a tendency to go overboard upon losing his temper, he had hurt a lot of people. He never considered Rhoda's feelings before hooking her up to his plant converter against her wishes, insisting she would like it. When he was attacked by mall shoppers in It's a Wonderful Leaf, he decided to take Christmas away from everyone, and he never considered the ones who didn't deserve it, such as Honker Muddlefoot. In Night of the Living Spud, when he found out Darkwing was making out with his potato wife, it sent him into a rage, and he tried to mow Darkwing down. He also desires vengeance, one of the biggest examples being Dr. Gary and Dr. Larson, whom he'd murdered after years of bullying. He seems to suffer from bouts of insanity as well, which may have been caused by his loneliness, pent-up anger and need for a friend.
Bushroot had a massive crush on Dr. Rhoda Dendron, a coworker at a university he worked in before his mutation. However, despite her expressing care and concern for him, those feelings were not reciprocated. He misunderstood her worrying about him as her expressing affection for him, and kidnapped her a few days after his mutation and, despite her protests, tried to mutate her against her will, until she was saved by Darkwing Duck. She was never seen again.
Spike is Bushroot's loyal flytrap dog companion. Despite that, the plant duck had not been shown to appreciate him, and would be angry at him if he made mistakes or annoyed him. Spike had assisted in many of his crimes and experiments, and would risk his life to help him escape if things went wrong. Bushroot's feelings towards Spike would eventually change as the series progressed. While he still did not see him as a friend, he started appreciate Spike for being dependable.
Darkwing Duck is one of Bushroot's greatest enemies. He despises how the hero would ruin his plans and call him 'mean names', like Bushbrain or Melonhead. However, there are times where he was willing to work together with Darkwing, or even help him.
They were bullies who loved to torment Bushroot and sabotage his experiments. Bushroot hated them with a passion and eventually got revenge when he discovered his new powers upon turning into a mutant, by strangling them to death.
Bushroot's boss, he seems to fear him and takes any abuse he dishes out without protest. Yet, sometimes, he would approach the criminal mastermind with enthusiasm, even if he was constantly met by violence or sneering. At one point, he was able to convince his team to kill Negaduck, but stayed out of the fight when his team took on Darkwing disguised as their boss, preferring to cheer from the sidelines. And when the real Negaduck returned, he completely lost his nerve and went back to following orders immediately.
He dislikes Quackerjack for the damage some of his toys had done to his plants, and is shown to be frightened by his rambunctious and wacky behaviour.
He rarely interacts with Megavolt, however, he had been heard to openly insult and attack the rat for territorial rights when the Fearsome Five had taken over St Canard.
Bushroot had assisted him in taking out the police station in Just Us Justice Ducks (Part One), where he seems to enjoy working with him. But there have not been any Bushroot-Liquidator centric episodes, so not much can be garnered from their relationship.
They had rarely crossed paths, but when she was accidentally mutated into a slime duck, Bushroot was eager to make her his friend. He later realised she may be in danger of disintegrating and attempted to cultivate her. Later, realising how much she meant to Darkwing, he released her and gave her back to him.