All I remember about this story (possibly a novel or novella, possibly by Poul Anderson) is that the butterflies on this planet are plants. The author uses a clever latinate word based on “phyto” to name these forms. Also, no one realizes the plants are telepathic.
Contact with the plants may be forbidden or deadly; may have been the first of two stories set on the planet. Sorry the details are so vague—I am sure I read it only once.