Photobiont

Part of speech: noun

Definitions

1. The photosynthetic organism, typically an alga or cyanobacterium, that forms the autotrophic partner within a lichen symbiosis
2. An alga or cyanobacterium that lives symbiotically in a lichen and produces organic compounds through photosynthesis
3. The photosynth­esizing component of a lichen, usually a green alga or blue-green bacterium, that provides nutrients to its fungal partner

Etymology: "Photobiont" is a modern scientific coinage, built from two Greek-derived pieces. The first, "photo-", comes from Ancient Greek "phōs", meaning "light", which traces back to a reconstructed ancient root meaning something like "shining" or "to shine." The second, "-biont", is a combining form from Greek "bios", meaning "life," used in biology for living organisms that take part in a relationship. Put together, a photobiont is the light-using partner in a symbiotic pair, most famously the algal or cyanobacterial component of a lichen, which photosynthesizes and supplies food to its fungal partner. The word thus describes a role rather than a species: it names whatever organism in the partnership captures light energy. The ancient Greeks had no such term; it was assembled in modern scientific English from classical building blocks.