I only recall bits of this one...
A father who lives in a world tree is telling (his?, all?) children about the weird people from Earth who have to fly in spaceships. He tells of an adventure where he had to work with Earthlings for a while.
Sadly, that's all I can recall. I read it in Omni, and it was the early 80s.
Hum, try this one (First in a series) "The Integral Trees" - https://en.wikipedia.org/wiki/The_Integral_Trees
An integral tree tuft is up to 50 kilometers from the tree's center of mass. Thus, a tuft is either orbiting too slowly (the "in" tuft) or too quickly (the "out" tuft) compared to the atmosphere, which is in orbit at all points. The ends of the tree are therefore subject to a constant gale-force wind that causes the ends to curve into the shape of an integral symbol ∫ and pushes water and food onto the tufts, or (less forcefully) onto the trunk, where the gravity-like tidal forces pull the material out towards the tufts. Each tuft serves several main purposes for the tree. First, the green foliage is photosynthetic, providing the tree with energy from sunlight; second, the tufts are where the tree produces its seeds; and third, various plants, animals, and sundry other objects can become trapped in the tighter branches, which gradually migrate toward the "treemouth." The treemouth, a pit at the top of each tuft on the lee side of the trunk, is the integral tree's root; water collected along the trunk flows down due to tidal forces and is ingested by the treemouth. Tuft branches catch and capture various things and animals in the wind and gradually, over the course of years, migrate to the treemouth, where they and their catch are absorbed by the tree for nourishment. Many other large Smoke Ring plants have a scavenger/carnivore aspect similar to this, though with somewhat different mechanisms.
The memories of the people involve Humans in Space Ships which feeds the last Book in the series.
Holding back vs Spoilers.
