Wander through the labyrinthine tunnels twenty feet beneath downtown Houston, and the past practically oozes from the walls. Office workers walk over pink-and-green speckled tiles. Steve Winwood’s eighties banger “Valerie” plays over a sound system. But next to the Smoothie King and across from a restaurant called Pastabilities that reeks of marinara, a door to a well-lit space displays a potential glimpse of the future.Bart Womack, a former nightclub owner and music event entrepreneur, is the founder and CEO of Eden Grow Systems. Inside his showroom, a gardener tends to three carts, each about the size of an office desk, from which a couple of dozen golden and purple flowers grow out of trays connected to the sides of the cart. Rather than extend into…