A Lesson in Genetics

Here's a fine example of Brassica oleracea:

Broccoli

And another:

Cauliflower

And another:

Kohlrabi

And another:

Brussels sprouts

And another:

Kale - in desperate need of fertilizer

Wait, these are all the same species?

Yes, yes they are. Over the centuries of domestication people selectively bred and developed this species into several distinct cultivar groups, each valued for a particular trait or part of the plant. Kale and collards are prized for their leaves, broccoli and cauliflower for their heads of pre-flower buds, and kohlrabi for its specialized stem.

Which may explain why this popped up in the kohlrabi patch:

The leaves look more like cabbage, but the stem looks like a cross between kohlrabi and broccoli.

Kohlrabi on the right and left, mystery plant in the middle

Even after generations of breeding, every now and then the DNA spontaneously mutates and a plant with different qualities grows.

Plant breeders would use this to their advantage, trying to develop a new cultivar or variety through self-pollination or cross breeding. If they had the right laboratory equipment available a geneticist may try to to sequence the DNA and identify the specific gene mutation.

As for me, it's proof I have no business saving seeds from my plants to propagate the next year's crop. Who knows what may pop up if the bees and bugs transfer pollen from one cultivar to another. I'm perfectly content buying my seeds from the fine folks at Gurneys, Burpees, or Park Seed.