A Cousin of the Cabbage
The kale plant is a very close relative of the cabbage, being, in point of fact, one of several related plants that have probably developed from the same wild stock, greatly modified through long generations of cultivation. Of the various cabbages, kale is perhaps the least generally known. For that very reason it should have exceptional interest for the amateur worker in the vegetable garden.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 7 Chapter 7