Can someone explain this collectible stuff to me?

[arc_08]

A level 51 botanist retainer can bring back 20 per hour. Its also very easy to collect with your own level 51 botanist. For higher level materials tho its indeed pretty much needed to have your own gathering classes leveled.

I regret not levelling my gathering classes. Any tips on the fastest way to get to 50 so I can start farming these stuff?