What about some tree- or bush-like structures that have lots of small lights, one under each leaf? Having many lights that could all be positioned and angled differently would let you direct the light to only where it's needed and create a smooth shaddow-free glow. And be pretty too! Like the Cave of Two Lovers @Gorgritch_umie_killa@aussie.zone posted. Individual lights could have different color and brightness too.
Depending on the kind of bio-engineering or fantastical biology in your world these could be completely organic, completely manufactured, or some combination like lights attached to trees/vines grown for the purpose.
If you're into sci-fi and Afro-futurism I really enjoyed Sweep of Stars by Maurice Broaddus (written a couple years ago; cool to see what a long history it's building on)