Because the planet wasn't green until the plants arrived.
An ambitious, long-term, multi-level environmental program was launched approximately 3000 ma (ma=millions of years ago). This initial green technology continued it's impressive environmental performance and proved itself a sustainable and sustaining product over a long 'real world' study. The various evolving life forms unknowingly appreciated the multi-function systems they employed to sustain everyday life such as 'thermal comfort systems,' optimal humidity levels, calm and speedy physical recovery from the dangers of the time as well as the way they often inspired innovative and creative thinking required for an eventual evolution to intelligence and accomplishment beyond imagination to those at the trial of the product. Great, brave and intelligent humans accomplished tremendous and wonderful projects. Much more recently a select group of these highly intelligent beings began to develop, own, design and manage commercial buildings...
Yet while we have no record of plants slowing down their environmental contributions, to no fault of their own, many professionals who even today determine what comes in and out of these structures, for some reason, grew to associate the green plant with a logo!
Humor aside, we are wise to thoughtfully reconsider the powerful, efficient, simple and clean technology of our green forefather when engineering our standards of a green building.
3000 ma:
Photosynthesizing cyanobacteria evolve; they use water as a reducing agent, thereby producing oxygen as waste product.[17] The oxygen initially oxidizes dissolved iron in the oceans, creating iron ore. The oxygen concentration in the atmosphere subsequently rises, acting as a poison for many bacteria.
