Germinating seedlings search for sunlight and grow toward it, quickly. Their desperate need for photons is made clear when I watch stop-action films like those available on the Plants In Motion website: http://plantsinmotion.bio.indiana.edu/plantmotion/earlygrowth/germination/germ.html. But once they mature, houseplants can hang on for a long time in darkish rooms with few photons-- they don't cast about so violently as those infant sunflowers when they first burst from their seed coats. They don't grow much, but they're more-or-less fine, just sitting in the corner.
Presently, I spend most of my time in dim environments -- the office, the lab, the living room, the bedroom-- where "photosynthetically active radiation" (PAR, to plant physiologists) is all but absent. Has my environment dampened my need for sunlight and fresh air? Is that a good thing?
(this is a test, really, just to see if this blog thing might work for me).