what is a stalk of celery

A celery plant consists of several stalks, and each stalk has several ribs. When a recipe calls for a stalk of celery, it is asking for one rib, not the whole head of celery. The term "stalk" in a recipe definition has diverged from the botanical definition, and it is now used to refer to a single rib of celery. The entire celery plant is not actually a "bunch" of celery, but a stalk of celery. When buying celery, look for fresh leaves and unblemished stalks, and the stalk or head of celery should feel heavy for its size.