Super vigorous kale plant

A couple of weeks ago I found this extremely vigorous brassica plant on a gravel pile. It felt like easily twice as tall and twice as wide as most other kale plants I have seen. Unfortunately the gravel pile was demolished before I could take a picture or measure the plant, but I did take a branch and put it in water, hoping to ripen some of the (very small) seed pods. The pods are growing, and the cutting also started rooting. Now I have divided the branch, planted the rooted lower part in soil and put the upper part back in water to hopefully ripen the seeds.

I don't know what type of brassica this is. Do you recognize it?

Possibly wild mustard -- https://www.eattheweeds.com/cutting-the-wild-mustard-brassica-sinapis-2/

or rapeseed?  https://candide.com/IE/plants/eaabf98455d9bdfef9c454fdb2d2c943

If that was growing at my place, we'd call it wild mustard until there was a reason to call it something else.

Not likely to be wild mustard or rapeseed. We don't really have any wild brassica here, so it's something that escaped cultivation, and I have never heard of anyone growing much of either of those in this general area. Also, the leaves are very mild tasting, no peppery taste like I'd imagine at least mustard would have. Tastes basically like kale (the reason I called it that in the beginning) except maybe even milder.

Looks a lot like wild-type Brassica oleracea, like here: http://valleynaturalist.blogspot.com/2013/12/wild-cabbage-brassica-oleracea.html Extremely lush, and no sign of senescence even if it had loads of flowers. Ooh, would be so cool if it turned out to be a true perennial! Don't know if that is possible...

it looks a lot like the collard-type kales we grow here (flat leaf). our winters are mild so they can live for several years.

Tereza Okava wrote:it looks a lot like the collard-type kales we grow here (flat leaf). our winters are mild so they can live for several years.

You mean they flower and still keep going the next year? I always thought they had a biennial life cycle mostly, and that the "perennial" types (Daubenton kale and such) are ones that don't flower in most circumstances, and that's why they don't die the second year?

No, they rarely flower. Often i rip them out after 2 years (they get buggy or ratty) and they haven't flowered. When they do flower, it's after multiple years and the plant will usually die after. These plants will grow from clones ("babies" appear on the main stem and can be broken off and planted to grow into mature plants of their own).