DND, Maurice didn't actually say it was likely that the toxin is in other parts than roots, just that in some cases it can't be ruled out. It's the same thing with the cats and daylilies issue. Although it seems quite possible that daylilies have been mistaken for Lilium, but because of variability in plant poisons and differing reactions based on individual consumers, whether animal or human, one can't say for sure that it can't happen to at least some cats, some of the time.
There's an interesting example of stypandrol poisoning in a daylily relative (the same toxin as hemerocallin in daylilies) in goats. The goats are only affected if they eat the plant during the three weeks it is in bloom. With red maple and horses, the leaves are only toxic if they are wilted and so on. It's so complex I don't think anyone would stick their neck out and say some adverse effect couldn't happen. Another example would be the anthelmintics that are given to dogs but cannot be given to certain breeds. Ditto the problem with dogs and grapes or raisins - not all dogs are affected but some are poisoned and so far as I know it still hasn't been established why. A complicated topic, unfortunately.
