The tree bears lightbulbs as fruit, signifying a wealth of ideas.
The last of the three rendered illustrations for Rainbow, later Prism. The metaphor is the oldest one in advertising and it survives here on execution: the bulbs are not stuck onto the tree, they are hanging where fruit would hang, at fruit scale, in fruit quantity.
The canopy is built from individual leaves rather than a textured sphere, which is what lets the bulbs sit inside it and glow through. It is the only light in the picture that behaves like real light rather than like cut paper. Everything else is the same construction as the other two: flat saturated ground, matte model, and a hole where a shadow would be.