Every alchemist would focus on the herbs which they used. It was just a major aspect of making a potion. However, they would usually trust what was known or focus any research on known aspects of the herbs in general.
Even when researching newer herbs or unknown herbs, the characteristics were easily discovered by referencing related or similar herbs. That being the case, those doing altogether new research were not actually all alchemists. It was better to say it was the herbalists who were leading that aspect of alchemy.
The herbalists were responsible for managing more than just growing the herbs. What they did could change the herbs at the core of what they were.