This blend file contains a node group which takes an original texture as input and can produce variations with different hues/tints. You can use a color as second input to get results like the red and blue leaves, or else a texture like for the Blender logo leaf. The 2 leaves in the back use a Voronoi texture, either directly or pre-tinted in orange. The "Power" setting of the node group controls the brightness of the result. (Values from 0 to 1 mean darker and anything over 1 means brighter.)

This node setup can be quite handy for particles, foliage or else.

Check also the material using the original texture to see how to use the alpha channel of a texture in Cycles without mask.

(Included textures are CC0.)

Enjoy!