Feather trees were first introduced in Germany and were made from dyed goose and turkey feathers. According to "Christmas Collectibles" by Margaret & Kenn Whitmyer, after WWI, Germany made trees as tall as eight feet and sold for about nine dollars. The first artifical trees were green, but in the 1930's different colors started appearing.

This tree is a faux feather tree, but is a good example of what the trees look like.

Feather Trees

More on Feather Trees by Ann Sizemore.
Connie Porcher's Feather Tree