>> Hypothetically, some of your chinese cabbage cultivars might be more closely related to some bok choy cultivars than they are to other cultivars of chinese cabbage.
I didn't know that.
I think the same thing happened with bacteria, and THAT drives me crazy, too.
Bacterial species that looked similar, acted similarly, and metabolized similarly used to be grouped together (functional grouping, or 'appearance grouping' I guess).
Then DNA testing showed that many similar-seeming bacterial species had evolved "convergently" (I don't think they use that word) to function similarly in similar niches, but came from very different ancestry.
I guess taxonomy "has to" follow actual genetic lineage, since it intends to reflect ancestry.
At least, using that standard, there can be only one right answer, even if you have to use statistics to guess which one.
(When I went to school, decades ago, it was just presumed that "looks like a Rarobacteraceae and quacks like a Rarobacteraceae" meant that they probably all descended from similar Rarobacteraceae ancestry.)
Brassica naming by the "looks like / tastes like / grows like" system was always a mish-mash of different systems and opinions (but functionally convenient for growers and cooks). The system of "Groups" seemed to me to have made sense of the confusion, with just a little "leakage around edges" for things like loose-headed Chinese cabbage, appropriate to a natural system, and thought to indicate "older" cultivars for the jaywalkers.
Maybe I should stop grumbling and just accept that not everything in the world exists for my personal convenience. In the case of Brassicas, especially B. rapa and B. oleracea , and use common names for comon purposes, when taxonomists say (correctly from their perspective) that a Turnip is a Chinese cabbage is Broccoli Raab is Yu Choy Sum.
Instead I'll probably use the common names plus the no-longer-accepted Group names, because I like them and they have functional value, and come pretty close to being unambiguous. I admit that I draw the line at using an old and bogus "species name" like "B. chinensis" as Linnaeus did (for Bok Choy and Coy Sum), or "B. narinosa" for Tatsoi.
