I have two peltata near my pond and they have behaved well and become nicely established over the last 5 years or so. Last year one of them didn't send anything up from healthy looking rhizomes and this year neither of them have sent up the flower stems they have done since planting. One of them does have one very pathetically sized closed flower starting to rise however. As I say, the rhizomes look and feel healthy. Anyone offer any suggestions ?