I saw this idea in the Spring issue of CardMaker magazine. You randomly stamp the flower and leaves on watercolour paper with VersaMark and emboss with clear or white embossing powder. Then you use a watercolour wash across the the panel for a rainbow effect. The pink rose was stamped separately and embossed with copper embossing powder, coloured with a deeper colour watercolour, then fussycut and popped onto the card.
Done for a card challenge at ScrapShotz - April Showers (bring May flowers)
Embossing Powders: white - Recollection; copper - ????
Distress Ink (used as watercolour): Tim Holtz
Sentiment Sticker: Tim Holtz
Watercolour paper: Canson