The shadow is interesting, sharp, and the stark contrast with the white background makes it grab the viewer's eye first. The flower is more subtle and doesn't stand out as much from its dark background so doesn't call immediate attention to itself, but is there to give an answer to the viewer's inevitable question of what the shadow is from, and is interesting in its own right as well as adding a splash of needed color. This image works very well for me.
This shot is really intriguing. The flower, unlike most of the others in the challenge, is interesting by itself and the way you've incorporated the shadow is also unique and unexpected. The only problem I have with it is that the composition seems a little bit awkward and unbalanced. But thats just my opinion. Overall, a top shot. 9