Brassica are the same way. Turnips, cabbage, bok choi, cauliflower, mustard, rapeseed, Brussel sprouts, kale, etc. Effectively all the same species -- hybrids

Brassica are the same way. Turnips, cabbage, bok choi, cauliflower, mustard, rapeseed, Brussel sprouts, kale, etc. Effectively all the same species -- hybrids or cultivars of a few wild ancestors that hybridize easily.