Leaves of extreme shade Selaginella tropical ferns change in improving light conditions from being iridescent blue to green by removal of photoprotective coating.

References

“Blue iridescence is most common in the genus Selaginella. The two taxa analysed here are native to the extreme shade of humid tropical forests: S. willdenowii (Desv.) Bak. in Southeast Asia and S. uncinata Spr. in South China. In both species blue iridescence develops on leaves in shade beneath foliage. The green leaves that develop in response to more direct sunlight do not become blue when subjected to this shade, but blue leaves gradually turn to green with age or exposure to more direct light (pers. observ.). The filtering action of the forest foliage produces an environment deficient in energy for photosynthesis, with only 0.1-0.3% of the light above the canopy (Bjorkman and Ludlow, 1972; Bazzaz and Pickett, 1980).” (Hebant and Lee 1984:216

Journal article
Ultrastructural Basis and Developmental Control of Blue Iridescence in Selaginella LeavesAmerican Journal of BotanyApril 21, 2006
Charles Hebant, David W. Lee

Journal article
Characterization of the light climate on the floor of a Queensland rainforest

No link available.

Journal article
Physiological Ecology of Tropical Succession: A Comparative ReviewAnnu. Rev. Ecol. Syst.July 2, 2003
F A Bazzaz, S T A Pickett

Living System/s

Organism
Willdenow's SpikemossSelaginella willdenowiiSpecies