Complete beginner in drawing looking for advice strictly for Pharmaceutical Botany

​Hi everyone,

​I started taking pharmaceutical botany classes this year, and I literally know nothing about drawing. I didn't even take art classes in high school. Even though our assignments don't require any shading or coloring, I really struggle to accurately transfer the specimens we're given onto paper.

​How can I improve my drawing skills specifically for this? I want to emphasize that I am strictly interested in botanical drawing. I have absolutely zero interest in learning how to draw animals, portraits, landscapes, etc. I just want to be able to look at a leaf, root, stem, or spore and accurately get its structure down on paper. ​What kind of roadmap or approach would you recommend for a complete beginner? Thanks in advance!