I have three Asamina Triloba trees in my backyard in Vancouver. They are not self-fertile but I know that all three are different varieties (one is NC-1; I don't recall the other two). Two are quite mature: about 5 m tall. But only one of them has ever flowered. And not even every year: every few years it produces several flowers. That is all. None of the flowers has ever led to a fruit. I assume that if another one flowered. they might fertilize each other and I would get fruits. But I can't understand why only one will flower, or why it only flowers every few years. Any ideas, anyone? .