Botantists are biologists who study the growth, reproduction, metabolism, development, diseases, ecology, and evolution of plants. They are integral to agriculture, forestry, gardening / horticulture, herbology and medicine.
The word horticulture is from the Latin hortus (garden) and cultura (from colere, meaning “to cultivate, tillage”.
The word agriculture is from the L. agricultura - ager+cultura = field (open land)+cultivate, and refers to the crops most economically grown (farmed - L. firmare “to fix, settle, confirm, strengthen”) in more open spaces like cereals and animal feed.
Forestry is the cultivation of trees and products related to trees. The term silviculture, specifically refers to the growing and tending of trees and forests. (William Penn received the grant of land that was called Penn's Wood, or Pennsylvania.)