Looking to study botany, some general advice
Have you checked out Botany classes at nearby community colleges?  You may have trouble finding an evening class, but I'm sure you'll find daytime classes opening up in the January.

If you need to study independently, can I suggest checking out the Tree Care Industry Association's store. www.tcia.org  They have various learning material to read and watch, leading towards a professional arborist certification.

Good luck in your endeavor.