What are three major areas of plant science?

The following all apply to plants. There are clearly more than three.

• Agriculture
• Biochemistry
• Biogeography
• Bioinformatics
• Biomathematics
• Biotechnology
• botany
• Cell Biology
• Conservation Biology
• Ecology
• Environmental Biology
• Epigenetics
• Evolutionary Biology
• Genetics
• Histology
• Integrative Biology
• Marine Biology
• Microbiology
• Molecular Biology
• Mycology
• Population Biology
• Phytopathology