Hello! I recently came across an article that said all members of the Cabbage family are able to breed with one another (ie cross breeding Broccoli with Cabbage). I was just wondering if you would be able to confirm this before I go out and buy seeds, as it would be fascinating to see some of the varieties that could be created if this information is true!
You are right, vegetables of the same genus and species (e.g., as you mentioned, broccoli and cabbage) can cross-pollinate. The genus (family) Brassica, in particular 3 species of this genus, B. oleracea (e.g., kale, cauliflower, broccoli, cabbage, Brussels sprouts, Savoy cabbage), B. juncea (e.g., several mustard varieties) and B. rapa (e.g., turnip, Chinese cabbage, pak choi) have been bred by humans through artificial selection for certain characteristics, including root production, leaves, flower buds and oil production.
Cross-pollinating plants (like those in the Brassica family) are those with flowers that need pollen from another flower (either a male flower on the same plant, or from another plant of the same species) in order to produce a fertilized seed; this is usually accomplished with the help of insects or the wind.
Here are a few references that might help you in your quest to cross-breed these vegetables. There seems to be little in the way of a “how to” manual, so I suggest that you speak with someone in the Botany department of your local college or university. They may be able to help you guide you in how to breed your plants for particular characteristics. For example, one issue you should consider if you want to cross-pollinate your veggies is that if there are other members of the Brassica oleracea family within a couple of kilometres, these plants could cross-pollinate with yours, and interfere with your plans!
Redwood Seeds’ Brassica Basics: Seed Saving 101 provides a good overview of cross-pollination. For example, by planting broccoli and cabbage adjacent to one another and letting them go to seed, you should end up with a hybrid seed that won’t be broccoli or cabbage (although it is not clear how robust the plants that grow from these seeds will be). The article also advises how to avoid such cross-pollination (e.g., to keep the crops true to seed – this is what most breeders want), by keeping the crops at a distance from one another, or only permitting one of each species go to seed.
A 2015 Business Insider article, These 6 common vegetables are actually all the same plant is an eye-opener, which explores the origins of several B. oleracea vegetables. Jeanne Osnas highlights this issue in The extraordinary diversity of Brassica oleracea .
See also the Populuxe Seed Bank’s handy Vegetable Cross-Pollination Guide .
Finally, the best information I located on how to artificially breed plants for particular characteristics was in a laboratory exercise from Colby College (Maine), Artificial Selection in Brassica, Part I – although this is not detailed enough to be a “how-to” article.