Words to Describe auxins

How auxins often is described ("________ auxins")

• acidic
• certain
• indole
• anti
• endogenous
• various
• extractable
• several
• diffusible
• containing
• potent
• natural
• active
• synthetic
• free
• exogenous
• related
• native
• weak
• pure
• different
• hetero
• other
• bound
• herbicidal
• neutral