The plant in this photo came to me as 'Ewiger kohl'. This is not exactly a variety name. It is German for 'everlasting cabbage' and was probably used in the past in the same way as 'perennial kale' is used now. Ewiger kohl, true to at least the spirit of its name, is a reliably long-lived perennial. Mine has never flowered and I propagate it by means of soft stem cuttings which take very easily.
Now that perennial kales with variety names such as 'Daubenton' and 'Taunton Deane' are being more widely shared, it seems that 'Ewiger kohl' may have become, by default, a name for the variety in the photo which does not seem to be any of the others! Searching for the name on Google will bring up photos of plants which look very much like this one. Googling 'everlasting cabbage' will do the same.
I get the impression that everlasting cabbage cuttings have been passed around from gardener to gardener in England, Ireland and Germany for many years. If you grow a plant that goes by these names it would be interesting to learn how you came by it and compare notes and photos. Do email me!
Compare my 'Ewiger kohl' and Daubenton kale in the photos below.
They are both obviously kale types but Ewiger kohl has smoother leaf margins, a rather more pointed leaf shape with a faint touch of purple about the stems and veins and the leaves are slightly thinner. In my experience they tend not to grow to the large size that Daubenton leaves can attain in a very fertile and moist position but they are more shade tolerant. Mine has been lower-growing than Daubenton but I have seen photos of taller plants. I suspect in time its floppy branches will root where they touch the ground although I don't think they have done so yet.
I don't know how they compare for hardiness - perhaps a hard winter of the future will answer that one!
In terms of flavour I would say Ewiger kohl is more cabbagey than Daubenton - but quite acceptable.
Also, although I regard Daubenton as a robust plant, I think Ewiger kohl is even tougher. Both types were hit really hard by mealy cabbage aphids in the spring and I eventually resorted to pruning them quite hard until they were more stalk than leaf.
This photo was taken just after the pruning. It has been the first to return to almost-full health - photo at top of page - (although the Daubenton is not far behind). Everlasting I hope!
N.B. I sell a range of perennial vegetable plants on my website.