My idea was that I would have a class which contains several lights as well as a particle system to represent an easily movable flame.
Just to add a bit more info. The flare images do not appear to have alpha with regard to other flare images. i.e. you can see through the image into the rest of the scene, but when two flare images overlap, you can see the square border of the foremost one over the image of the back one.
Transparant object have to be sorted before being drawn, because they have to be rendered from back to front. jME has a renderqueue you can use for this. This could solve your problem.
Look at TestRenderQueue (in jmetest.renderer) to see how this works, and it might help you understand why it's needed.
That looks like it may be exactly what I need. RL is calling, but I will try it out and post the results as soon as I can.
You're using the particle system so I doubt it will help much.
However it might be a little more obvious than that. You're using a JPEG so I doubt it has any alpha channel. What you're seeing could just be the overlapping of semi transparent pieces of black, no? What kind of image are you using?
I think something that most people miss as well is that you don't necessarily need graphics with an alpha channel. Blending can be done with the color intensity of the image as well. Alpha is generally easiest to get right though.