I've virtually finished this larger pastel of the willows now. It's 16 to 18 inches, though I haven't actually measured it yet. There's a write up here. It was done mainly in Unison pastels as I love their rich velvetiness and the way they don't disintegrate like some brands.
I wanted to catch the cold pale colours of the landscape and sky with the dramatically silhouetted pollarded willows with the warm late sun amber on one side of them and the cold sheen of the water behind.
I'm also working on a linoprint of these trees - you can see an early stage pencil rubbing of it here.
These trees aren't traditionally beautiful (they were up to last Spring :>( they were BIG trees) but the whippy branches slice the sky into little triangles and geometric shapes and they are very interesting to draw.
update: linoprints of the willows here