Herbology is the study, along with the use, of magical and non-magical plants. All plants may be for medicinal, protective, educational, or purely decorative purposes. For example oleander -- a very common and equally poisonous garden plant -- will kill you just as a Venomous Tentacula would.
Basic Herbology protection includes dragonhide gloves, earmuffs, and a wand. When doing practical work, it is safest that you wear closed-toe shoes and an apron.