Hello awile ago I posted something on a Demiplane/Plane of wood and an alternate planar setup but I had an idea to make a canon article that fans of the inner planes could enjoy without changing the inner planes at all.
Elemental Wannabee Demiplanes
Wood
this plane is a banyan tree with no known root or crown. Seemingly infinite branches spiral like the trunks of Yggdrasil into the distance, and plants of all sorts grow on the trunk.
Home to Treants, Shambling Mounds, and Plant-Creatures of all sorts, in addition to nearly every kind of Plant species found on the Prime, this place is a druid's best dream come true.
The mysteryious Shad live here in much greater numbers than those found on Elemental Earth, in addition, the Shad found here are slightly taller, and have more greenish skin tones.
The Demiplane of Wood shares a close ethereal border with the positive energy plane, fire, water, earth, air, and negative energy plane
Demiplane of Flowers: The nearer to Positive Energy one gets, the more the plants take on a pleasant, flowery feel to them. The natives also have this quality. Eventually, the branches of the plane end and one comes to an endless field of flowers. This is the Quasi-Elemental Demiplane of Flowers.
Demiplane of Blight: Going in the opposite direction, the plants start to wither and die. Poison seeps from their decaying remains. Not a pleasant place at all. This leads to the Quasielemental Demiplane of Blight.
Paraelemental Demiplanes:
Coal: The nearer one gets to the border with Fire, the more hot, black, dead and lifeless the branches of the plane seem to get, eventually the branches end, and one gets to a nearly endless sea of coal, which get more red and hotter the closer one gets to Fire.
Pollen: The nearer one gets to the border with Air, the more clouded the area around the branches seem to get with yellow clouds. Eventually, the branches end, and one arrives in the endless yellow clouds of the Paraplane of Pollen. This clouds begin to dissipate the closer one gets to Air.
Soil: Going down the Great Tree that is Wood, one eventually finds that the branches of the plane become engulfed in dirt. The Paraplane itself lies beneath this. It, like Elemental Earth, is nearly an endless expanse of solid earth. In this cause, the "Earth" is grainy and soft, and can be easily dug threw. "Roots" from the Plane of Wood can be found in various sizes the closer one gets to Wood, while the Soil gets harder, larger, and more rocky the closer one gets to Elemental Earth.
Coral: When one travels on Wood towards the border with Water, one may notice nothing at first, other than the fact that the branches of the Plane seem to be going downward. Eventually, colorful growths begin to appear on the branches, and then finally, the branches end, and an endless sea begins.
The Para Demiplane lies beneath this sea.