I read the story in a collection of stories in a book about 25 years ago.
It takes place on a dry world.
The flower keeps asking to be watered, it may have been using telepathy.
I'm not sure if the flower was on a vine.
The person waters the roots, which are some distance from the flower.
The flower keeps saying something like “Why are you not watering me?”
The person carefully follows the stem from the flower to the ground, and finds
that the root of some other vine was getting watered.
