Possible Clues:

• Shrub flourishing is in teapot
• Shrub by Italian river, in group about small island
• Plant with showy bracts, usu. red, pink or white
• Shrub is in teapot that's cracked
• Shrub planted in West, possibly, a long way back
• Plant in peat, so it develops
• Tiptoe in as going to pot plant
• Plant often given at Christmas
• Shrub often given at Christmas
• Petitions about a floral decoration