I've only had a reason given for one rejection from the pentax gallery, and that was "distracting elements in frame". I think that's your problem with the first one. It's a stunning blossom, but the background is too busy.
I know that's repeating what everyone else has said, but I did get that criticism from the gallery itself, so I think it's something they're looking for. Two of the four of mine that they accepted are very clean and simple, the other two are dramatic clouds which I didn't think were worthy, but was encouraged to enter and didn't they go and get accepted!
This all suggests to me that they're looking for drama or simplicity. I'd test the theory if I had time to take a decent photo, but I've been crazy busy and everything lately has been more or less of a snapshot. Ah well, we all have slumps. Keep at it, think drama and simplicity, and I bet you'll get one in. Good luck!
Julie