needrain said:When parentage is written "Aloe x Tulista x Haworthia", how would you read it? Aloe X (Tulista x Haworthia) or (Aloe x Tulista) X Haworthia? I'm assuming such a hybrid has either a pod or pollen parent that's either Aloe or Haworthia crossed with a hybrid of the other two given. Is there a rule that tells that in the way it's written? Inquiring mind at work here 
I gather that here that is not certain, so it's possibly a mix of three species. But if it were known, would be written differently.
Yes, I would think the name without parentheses indicates the genera involved, the name with parentheses indicates the order in which they were combined. Maybe one would alphabetize the names in the first case so to avoid implying any other kind of order. In addition to the two options you mentioned, it could also be Tulista x (Aloe x Haworthia), conceivably. The name before the "x" would be the pod parent, the name after it would be the pollen parent, so the 2 names around each "x" could be reversed and it would have implications for how the breeding was done, but not the genera whose DNA is represented in the multi generic hybrid.
Presumably the mitochondrial DNA is inherited maternally for most angiosperms, like it is in humans. (Your mDNA comes from your mother.) That tells you that the first name in any complicated cross (when it is provided in the order the plants were bred, with parentheses if necessary) is the one responsible for the mitochondrial DNA in the hybrid. A little bit of random detail there, a distinct outcome determined by which parent produced the seed. Curiously this pattern is reversed in gymnosperms, where the last name in the list (the pollen parent) is responsible for the mDNA.
