[Senator Bedfellow]

...farmers who had invented broccoli by crossing a cauliflower and a pea.

Seems unlikely. From investigating why my cabbage failed, I can tell you that kale, cauliflower, cabbage, Brussels sprouts, kohlrabi, and broccoli are all the same species of plant, Brassica oleracea, all descended from the wild cabbage of southern and western Europe. Its closest relatives, also in the genus Brassica, include wild and cultivated mustard plants, B. napus (the rutabaga), and B. rapa (the turnip). Trivia for the day :)

[blam]

Well, I read that all these vegetables were developed from a wild cabbage plant in England: Cabbage, Broccoli, Cauliflower, Brussel Sprouts and Collards. In fact, this was a correct answer on a question from the game Trivial Pursuit.

[aculeus]

...farmers who had invented broccoli by crossing a cauliflower and a pea.

Seems unlikely.

More likely: the family was adopted by one of the broccoli plants.