I never understood what makes a cultivar different from a species.

My understanding is that species delineates “breeding boundary lines” and cultivar are “pushed gene expressions”.

Take freshwater hobby shrimp. You can relatively quickly breed them to express certain colors (cultivar) but without some gene editing you can’t cross breed caridinia and neocaridinia (species).

And if you mix up the pushed color cultivars in a few generations they are very close to “wild type” again.

Such a shame that many cannot eat a lot of those plants because of their vitamin K content.

Would you mind expanding on that a bit? Is the vitamin k too high?

Some quick googling leads me down a kidney disease rabbit hole...which may not fully align with your statement.

Vitamin K cancels the effect of warfarin, which is the main blood thinner older people tend to get put on for various reasons. So eating vitamin-K rich foods ends up allowing blood clots to form

>cabbage, broccoli, cauliflower, kale, Brussels sprouts, collard greens, Savoy cabbage, kohlrabi, and gai lan

Ah, the gag me group.

I naturally find the smell of these cooking in the kitchen more repulsive than pure benzene in the lab.

I prefer a bit of prepared mustard myself.