Invisible object, visible texture, how?

I got a texture of a leaf with alpha channel. But when I apply the texture to a plane, the default gray is visible where the leaf is transparent.

Turning material alpha slider to 0 will make the texture invisible as well. So how to make the object invisible, and only the texture visible?

you will need to map it to the alpha as well as the color



So what do I have to do, exactly? I have checked both “Col” and “Alpha” in “Map To” panel.

EDIT: Turned alpha slider to 0, renders correctly.