Sorry, i meant point sprites, i'm kind of new to directx.
I tried your example, it didn't work.
I can edit the texture by hand and simply give it an alpha channel, but since there is actually 180 of them, that would take too long time unless there is an automated batch file that does it for you. The reason there are so many textures of one single tree is that i am trying to do an experiment to make 2D trees look more realistic. I have made a texture sequence of a tree from 180 different angles. The tree switches between those textures when the angle between you and the tree changes.
The texture sequnce is directly exported from a 3D program called Terragen as a .bmp format. Those .bmp files had no alpha, so i tried improvising to make the textures transparent. So far i have failed.