Persisting after cultivation. Daylily is said to be sterile across all territories outside its native range. All plants in Europe and America are thought to be progeny of a single cultivated plant, an infertile triploid. Daylily has been, however, doing very well and managed spreading. Occasionally, it is hard to imagine that isolated solitary plants found in natural habitats just persist after cultivation; yet they might have originated from vegetative parts.