It’s fair to assume that like in new leaf flowers remember their parents meaning:Yup I saw that chart too and while it seems like it could be accurate, I feel there are other combos to breeding the same flowers. Example being
Red+orange = black lily
Pink+orange = black tulip
Would love to see a compilation of all known (non mystery island based) combos. As that’s something that I’ve not seen any guide doing yet.
Red and orange for black works because orange is had a red parent and pink and red making black works because of its red parent.