Botany

I would suggest doing MS or equivalent in the field of natural products chemistry. It is a fascinating subject that includes though not exhaustively, the investigation of useful compounds in herbs, plants, living specimens, trying to figure out its in vivo biochemistry and working out a viable synthesis in labs. Although, I must say two things:
1. Any chemical specialisation is bound to exclude the real beauty of botany: the study of diversity and evolutions in the plantae. So, you may want to consider that.
2. A lot depends on your real specific interest in chemistry. Do you find biochemistry fascinating? Or is it inorganic chemistry that piques your curious side? Before venturing into a dual delight, think if you are really interested in biochemical sciences. It is a burdensome major if you do not have interest in it. A final tip: You may still want to consider choosing one of these interests, in which case, an MS in your specific interest in Chemistry is to be found. Investigate the various chemical sciences. Some biggies are: Physical Chemistry (Kinetic studies, Quantum Chemistry, Nano chemistry, Thermodynamic and Chemical Energetics), Inorganic Chemistry (Organometallics, Coordination chemistry, Classical inorganic chemistry), Organic chemistry (Natural Products, Biochemistry, Organic Synthesis and Catalysis), Analytical Chemistry.
Thank you.