Acorna's World   by Ann McCaffrey, Elizabeth Ann Scarborough

Believe this plotline if you can. There's this woman called Acorna (dunno why; maybe it's because she's got this great mass of white hair and a bloody great horn sticking out of her forehead), and some bad guys are after her and her posse. They find themselves crash-landing on a planet, and after a period of time work out that the flora are intelligent, and that they can communicate with them. The flowers have the potential to dispense some powerful potions, and can physically grapple people as well. So Acorna's people persuade the plants to attack their pursuers, and entice the pursuers down to the planet's surface... You can guess the rest.

What a complete load of mush.