It is botany.
Botanist
There are a few fields of science that study tree branches. One of the most common is dendrology which studies the science of wooded plants much similar to plant taxonomy.
Social Studies of Science was created in 1971.
Horticulture is the science that deals with the studies of plants. This includes things like herbology, silvoculture, crop science, pasture and rangeland science and management, plant biology, etc.
Science Fiction Studies was created in 1973.
It studies the interactions in groups of humans. And, therefore, is a science. "If it studies any thing science may it be."
A scientist is someone who studies science.
Science
Society for Social Studies of Science was created in 1975.
Institute for Cognitive Science Studies was created in 1998.
A person who studies Political Science is called a political scientist.