What do botanists do?

look for plant material.

Archeology and botany have nothing to do with each other. Botanists study and tend to plants. Archeologists dig up bones, fossils, and other items to study ancient history.

Botanists study plants. And yes there is a role for botanists in archaeology. A botanist can identify plant fragments such as clothing fibers, food remains, even something as small as grains of pollen. Archaeology is very much a forensic science these days and much of the work takes place in a laboratory, looking down a microscope.

@silverfly is speaking more of paleontology than archaeology.

@downtide Thanks for the clarification.

they study different plants, and their surroundings.

Plants, how things interact with plants, agriculture, etc.

Often they’re useful in archaeology because they’re able to assess what the environment was like from the species of pollen and wood found.
When it comes to mummies they cab identify pollen, paper, non-wool cloth, occasionally plant dyes, wood, oils, and give more information about what was there at the time of the entombment.

Study the botfly.