I really liked the trees along the front at Manly Beach. This, I thought, was a particularly impressive tree, obviously straining to get to the beach itself.

What I specifically liked was the shapes the trees made against the harsh, Wintery skies. Look at this example:

Here's the exact same picture rendered in high contrast tones using standard digital magic:

One more example:

You can get similar effects using leaves and photo-sensitive paper, or leaves and aerosol spray paint.