The Sun is not a reliable news source. They're running a picture of what looks like trees with no explanation of what it actually is.

http://math.ucr.edu/home/baez/week290.html (scroll down to the bottom)

"It would be great if there were trees on Mars, but it's not true. In fact what you're seeing are steep slopes with dark stuff slowly sliding down them! Here's a description written by Candy Hansen, a member of NASA's Mars Reconnaissance Orbiter team at the University of Arizona:

There is a vast region of sand dunes at high northern latitudes on Mars. In the winter, a layer of carbon dioxide ice covers the dunes, and in the spring as the sun warms the ice it evaporates. This is a very active process, and sand dislodged from the crests of the dunes cascades down, forming dark streaks."