Weeping Rock

This is part of a canyon wall was dynamited to make way for the Garden Gulch Road in Parachute, Colorado. In the spring, as the snow melts, the water seeps through the cracks of unstable siltstone some 100' from the top. On the wall, you can see grass and scrubs growing. To me, this is such a work of nature. How life will thrive even where it wouldn't seem possible. Is the grass species imbedded in the rock from centuries ago? The scrub that is growing doesn't resemble any of the scrubs from the area. Where did it come from?