I can't help thinking that this is about a car crash. A couple who is going through problems but are still "tangled" in the relationship is in a car on a wet road, which loses traction and crashes into a tree.
The relationship started as just a normal, healthy, "straight line", but kept on getting more and more complex, and the straight line got tangled up and spiraled out of control. "Spiral spin" can refer to both the out of control car spinning off the road and the relationship spinning out of control.
The panda, or the woman in the relationship climbs the tree, gets away from the ground, where the wet worm, the man, waits for her to come back to the ground. But she lives a life in spite of him, and won't come down. I think the fruit bearing seed could be talking about her other lovers, and how she refuses to eat any of the "fruit", meaning that despite all the lovers who bear her love, she won't devote herself to any of them.
As the singer gets out of the car and looks at the wreck, he sees the leaves on the ground and their fall colors mixing with his (ex?)lover's blood.
This song is really haunting, and I love how up to interpretation all of it is.