Recently a trip to the Huntington Botanical Garden opened my eyes to the multitude of plants that i've never seen or heard of. One such plant (Ecbolium viride) made me consider the varied pigments that are nearly unknown to commercial horticulture. Blue color in plants is derived from anthocyanins such as Delphinidin and Malvidin. Delphinidin was first isolated in the Delphinium flower, and the genetic inability to produce this chemical prevents blooms such as roses from ever naturally occurring blue. Some plants make better use of their Delphinidin than others to create a color not often seen in nature: cyan.
Could specialized color expression be an evolutionary mechanism not being utilized to its fullest? Trichoderma viride, a parasitic mold displaying a unique shade of aquamarine, has been found to possibly combat the soil pathogens rhizoctonia and armillaria.
Also: Cyanobacteria had it right at the start, and it's in it for the long run.