Possible Clues:

• Silence
• On the q.t
• Tight-mouthed
• Not exactly talkative
• Whichever way you look at it, it's one of the relative's tips for making up mind
• Mother's Day flower, in Australia
• Quiet member of the family?
• Is tight-lipped, as there are no campers in summer camp
• Dad's mate, to a Brit
• Fall bloomer, familiarly