Root System Vigor in the Cabbage Family

Wild cabbage is a weed and grows like one, able to successfully
compete for water against grasses and other herbs. Remove all
competition with a hoe, and allow this weed to totally control all
the moisture and nutrients in all the earth its roots can occupy,
and it grows hugely and lushly. Just for fun, I once G-R-E-W one,
with tillage, hoeing, and spring fertilization but no irrigation; it
ended up 5 feet tall and 6 feet in diameter.
As this highly moldable family is inbred and shaped into more and
more exaggerated forms, it weakens and loses the ability to forage.
Kale retains the most wild aggressiveness, Chinese cabbage perhaps
the least. Here, in approximately correct order, is shown the
declining root vigor and general adaptation to moisture stress of
cabbage family vegetables. The table shows the most vigorous at the
top, declining as it goes down.