They grew on the bridge

Out on Seven Mile Bridge, close to Marathon, FL, a few natural phenomenons grow out of the concrete mass of an abandoned railroad track running beside the bridge. A tree and a few shrubs have made the old tracks their home. Driving over the bridge, your eyes take a second look to make sure what you are seeing is real.

It is real, and a view from a boat helps to make the illusion reality.

How can something that needs nutrients and fresh water grow in the concrete? How did the seeds of the plants reach all the way out across the bridge and survive?

I'll probably never know the answers, but would love to return after many years to see if they still survive, and if there are any new ones growing.