I am currently making a mini resource pack for Minecraft 1.9 and when I got to the Elytra I was thinking of making it so players could have a different texture for the item depending on what name they gave it in an anvil. So like maybe when they get the Elytra its whatever default texture I decide to give them but then if they take it to an anvil and rename the Elytra to say... Grass Wings it changes to a more green version of the Elytra.
I don't think you can do this, but it would be possible to use a command block to create green particles (try HappyVillager) around the "leaf Elytra". I would suggest using a command generator (like "MC stacker") to make this command, and no mods/plugins/resource-packs should be requred for this method. The only problem is that the Elytra will never change color, just look epic on the ground.