Drifting Seeds

As the cottony, parachuted seeds of the World Tree drop, they become one of the favorite haunts for fairy folk to host their never-ending revelries. The seeds take several days to drift rootward, and as the night rises, bonfires are lit atop the seed coating. Fairies dance along the spindles of the parachutes and when the seeds get too close to the gloomy roots, the fairies simply fly crownward to another seed and continue their party. Many foolish souls are lured by the ethereal bonfires with no way to cross the space between.
Mysteriously, no one knows where the seeds end up when they fall. To that same mystery, none have ever seen one of the seeds sprout, or any other world trees beyond the sky. It is possible that only the fairies know where the seeds go. If they do, though, the fey will never say.

Geography

The seeds are relatively small areas, covering only the space of an acre or so. At the center are the pericarps of the seeds, which bloom out to spindly white strands called the pappi (individually pappus). The pappi have feathery extensions to keep them aloft longer as they fall rootward.

Ecosystem Cycles

These regions become more common when their side of the tree is experiencing Spring or Autumn. Seeds can be blown about and fall out of season as well.

Climate

Inhabited seeds are kept comfortably warm from the fairy bonfires, but have brisk winds at the ends of the pappus that are exposed to the Space Between. The seeds don't have their own weather, and are subject to whatever weather the region they are passing experiences. If the weather is poor, it is likely to drive away fairies, who will seek better places to hold their bacchanals.

Tourism

Many people can see these seeds in the distance at night. Wisps of music reach them from the Space Between. The joyous parties of the fey instill a longing in those stuck on the Tree. A pull to join the dancing fills the chests of onlookers, but very rarely is a seed close enough to join. On occasion, a fairy will invite a mortal to join in the revelry and take them to the seed. These dances are legendery, in several senses. The celebration can naturally lay powerful enchantments on the mortal guests, even if not intentionally or maliciously. This is part of the danger of this revelry; given the capricious nature of the fey, it is not a given that a mortal will be returned to where they came from when morning comes. Fey tend to disappear during the day, and do not always return to the same seed the next night. An unlucky tourist may find themself trapped and alone as they are too far to jump to the tree, doomed to fall to the dreaded Roots or beyond.