I have a three-year-old white carnation type tuberous begonia that has an odd growth pattern last year and this year. The leaves and flowers are just jammed together on top of the stalk. The leaves don't have room to open normally. They're sort of pleated and shortened and the flowers also don't open properly, but are oval with short petals. The centers of the flowers also seem hard, almost vegetative.

Any ideas what ails this plant? None of the others have the problem.

Thanks.