The only groups of the plant kingdom which are known to produce light are some of the bacteria and some of the fungi and the dinoflagellates (Peridineæ) if one is to include them among the plants. Many different species of phosphorescent bacteria have been described, differing in cultural characteristics and structural peculiarities and grouped in the genera, Bacterium, Photobacterium, Bacillus, Microspira, Pseudomonas, Micrococcus, and Vibrio. Specific names indicating their light-producing power such as phosphorescens, phosphoreum, luminosum, lucifera, etc., have been applied.

All the fungi which are definitely known to produce light belong to the Basidiomycetes, the largest and most highly developed of the true fungi. Either the mycelium alone or the fruiting body alone, or both, may be luminescent.