You can also bonemeal End Stone and that will grow an ender flower (only works if you're in the end)
On its own it's only a decoration block (even that might not be true since you can only place it in the end)
But it's used on several dyes recipes named bellow!
In the Ender Furnace you can smelt an ender flower with any dye to get two of that dye!
Every dye requires only 1 ender flower. Lapis is the only one that requires 2!!!