A stalk of brussels sprouts photo credit: cbmd, flickr (click for photo in original context)

Last week Greg over at Pie-ence was talking about the amazing variety of vegetable crops breed out of a handful of species within the genus Brassica, specifically Brassica rapa and Brassica oleracea.* I’m referring to these as cruciferous vegetables, which is actually a wider category including all the vegetables within the mustard family of plants (scientifically this is called the Brassicaceae). But one of the cool things about having so many kinds of vegetables within the same couple of species is that, because they’re the same species, they can still be interbreed with each other to create “new”** vegetables.

I still remember the first time I saw such a new vegetables, the broccoflower***. I didn’t even LIKE vegetables back then but I was still fascinated by this strange new plant in the produce aisle. Needless to say, others didn’t share my excitement as the broccoflower did not, in fact end up taking the world by storm (I’m not bitter!), although I do still spot them from time to time at the grocery store. I was able to dig up this very enthusiastic article on the broccoflower from twenty years ago. The internet is a wonderful thing.

The internet is also responsible for telling me about the latest development in cruciferous vegetables. The “flower sprout”, the result of breeding work using brussels sprouts and kale, both breeds of the species Brassica oleracea. Right now they’re only available in England, otherwise I’d have tried it already. How could I resist a vegetable described as:

“a purple and green triffid-like crop”

Assorted colorful cauliflowers (orange ones make lots carotenoids the group of molecules that includes pre-vitamin A, the purple ones make anthocyanins another kind of plant pigment). photo: Le Grande Farmers' Market, flickr (click to see photo in its original context)

Both the links in the above paragraph are to stories that also contain pictures of the flower sprout.

I guess my point here is that plant breeders can produce all kinds of cool new vegetables given the chance. The limiting factor really is what people will buy, not the variability of plants.

*Brassica oleracea is responsible for Broccoli, Brussels sprouts, Cabbage, Cauliflower, Collard Greens, Kale, and Kohlrabi. Brassica rapa is responsible for Bok choy, Komatsuna, Mizuna, Rapini, Chinese cabbage, and Turnips. And Brassica napus, a species that resulted from the hybridization of Brassica rapa and Bassica oleracea adds Rutabaga and Canola (not a vegetable, but a key crop none the less) to the count.

**I’m putting new in quotes throughout this article because I don’t know what the actual definition of what makes vegetable different enough to qualify as a new type is.

An Arabidopsis flower (also a member of the mustard family that produces so many kinds of vegetables). The name cruciferous vegetables comes from the pattern of four petals. Apparently it looks like a cross to some people, hence cruciferous. In Arabidopsis the flowers are only a few millimeters big. photo: BlueRidgeKitties, flickr (click to see the photo in its original context)

***From everything I was able to read the broccoflower really is the result of a cross between broccoli and cauliflower (followed by many more generations of selective breeding of course). It is generally lumped in with the cauliflowers because its head is made of up inflorescence stem tissue, while broccoli heads are made up of immature flower buds. Cauliflower plants (and broccoflower plants) have broken copies of the CAL gene, which (when it isn’t broken) is helps the plant decide to switch from producing stems that were bear flowers to the flowers themselves. Without a functional version of CAL, cauliflowers just keep making denser and denser stems, producing the distinctive heads of cauliflower. If you have journal access, you can read more about the CAL gene at this science paper: http://dx.doi.org/10.1126/science.7824951

Since the effect of breaking this gene suggests to me that it is probably a recessive mutation (it won’t have an effect on the plant unless the plant inherits a broken copy from both parents) I imagine developing the broccoflower involved mating the offspring of a broccoli / cauliflower mating and mating them with normal cauliflowers again, since plants with one cauliflower and one broccoli parent should inherit a working copy of the CAL gene from their dad (or mom) the broccoli. But this last paragraph is purely my own speculation.

Consider the case of the cauliflower. At my local grocery I can now purchase that particular vegetable in four different colors. In addition to the traditional white, there are orange cauliflowers, green cauliflowers, and purple cauliflowers. Guess which kind I get?

Purple cauliflower one of at least four colors now available

I’ve already shown you the range of colors carrots come in, but to me the purple ones look more exotic than white or yellow. Purple potatoes have also been touched on, but it was a while ago, so here’s the picture:

Purple potatoes with orange carrots

There are of course also purple corn chips and purple rice, and dozens of others I’m not thinking of tonight, but what got me thinking about this subject as a post over on the Agricultural Biodiversity Weblog that pointed to this story on a Kansas State sweet potato breeder who is trying to develop breeds of purple sweet potatoes suited to local commercial production. Now he’s got a motivation most of us don’t, K-state’s single school color is royal purple.*

But what about the rest of us without Purple Pride (assuming it’s not just me to thinks purple vegetables are fascinating)? What is the attraction of purple (and other unexpectedly colored) vegetables?

*In all fairness, he’s also motivated by the health benefits of increasing the consumption of the anthocyanins (the compounds than make most purple vegetables, and flowers, purple), and the financial benefits for local farmers if his purple sweet potatoes provide a way to differentiate their sweet potatoes from all the others on the market.

More purple plant photos:

The little miracle of forbidden rice. I still need to write the post on this.

It's not just corn kernels that can be purple. Some gene variants make the whole plant purple!