The Alchemist brews potions at brewing stands for you. They can also collect mistletoe (1/30 chance) and netherwart (1/60 chance) using shears. They can make potions used by Druid.
Note: The Alchemist can only learn a set number of recipes based on their hut level. So:
The higher a Alchemist their Dexterity level, the faster they will brew each potion. The higher their Mana level, the more brewing stands they can use at once.