When taking a botanical art class your teacher will often recommend a paper suitable for the medium being used—one that will achieve the best results. Sometimes it will depend upon the class skill levels.
Like all things, personal experience comes into play, and experimenting can be fun. I’m no expert, but it would seem that the best paper choice for each of the various media would be paper with a smooth, not rough surface—one that complements the techniques applicable to a chosen medium. For example, hot press paper, used for watercolour, is smooth which makes the application of delicate details easier. Choices may also change as skill levels improve. Paper choice is a big topic, and I’ll leave that for an expert.
I have always been curious about how paper is made and recently came across this article which explains it very well. Enjoy!