Short answers, pulled from the story.
Carl Linnaeus described the species Apium graveolens in 1753 within Volume One of his Species Plantarum. This scientific classification placed celery within the family Apiaceae alongside other aromatic plants.
Farmers grow stalk celery for its fibrous edible stems, leaf celery for its aromatic foliage, and celeriac for its large hypocotyl root. These three groups represent the selective breeding of the original wild species over centuries.
Raw celery consists of 95% water with 3% carbohydrates and 0.7% protein containing negligible fat. A reference amount provides 14 calories of food energy while serving as a rich source of vitamin K at 24% of the Daily Value.
Daniel Zohary and Maria Hopf note that celery leaves and inflorescences were part of garlands found in the tomb of pharaoh Tutankhamun who died in 1323 BCE. Literary evidence indicates cultivation existed in Ancient Greece where Homer described wild celery growing in the marshes of Troy.
In 1986 the U.S. Food and Drug Administration banned sulfites on fruits and vegetables intended to be eaten raw. Restaurants previously stored celery in water containers with powdered vegetable preservative causing allergic reactions in some people.