How can plants survive without sun?

I work in a jewelry store enclosed inside a mall. There is no sunlight anywhere, but we have three plants that have been living here for the better part of a year with only water. I was wondering what they're living off of? One plant is a hanging fern, well, actually, a cutting from one. It's one limb that's floating in a jar, no dirt or anything. There are two other potted plants, but they get nothing but water. Are the lights in jewelry stores enough to feed them?

How can plants survive without sun?
There are many houseplants that do not require a large amount of sunlight to survive. Plants with low light requirements can survive with the amount of light they are receiving from your store's artificial light. For example, a plant that needs 4hrs of sunlight can survive with 8 or more hours of artificial light. I don't know what plants you have, but I am sure they would benefit from some fertrilizer. The plants are getting some nutrients from the soil and water, but eventually the plants will start to decline.
Reply:Some plants can live without soil because they used oxygen/CO as a nutrients to growth. Maybe artificial light help it to growth. Or maybe its your smile that the plant drawn nutrient from cuz it bright up the place like the sun.
Reply:a lot of plants do well living from artificial lighting. such as florescent bulbs.