Not an expert here , but the two last ones remind me of water lilies.. could it be that?

This may help...

Here is a link that might be useful: Skylined's ID

Try posting on the 'Name that plant' forum. The last 2 definitely look like water lilies.

WW

second one looks like a Melastoma, aka Tibouchina.
Kris

First one is a Clerodendron. It is hard to be sure without foliage in the picture and some sense of scale - maybe C. paniculatum. Second is a member of the melastoma family. Tough call on such a close up of an unopened flower - probably a Rhexia. Weedwoman is right - the last two are definitely waterlilies. This is as exact as you can expect with photos that show so little of the plants.