It's a nice spinach plant for cold climates.
I got an email:
"you are one of the only people on the internet that knows anything about Hablitzia tamnoides ... i would like to know more if you are willing to share your knowledge:
- is it perennial?
- will it grow in zone 6?
- can it tolerate shade?
- does it taste good?
- can american gardeners get the seed?"
2) It will grow in Helsinki, Finland, Europe. I don't know this "zone 6" of which you speak.
3) Dunno, we've grown it in full sun. Note, that's still Helsinki, Finland, Europe. If you're in, say, Arizona, USA, North America, or Sydney, NSW, Australia, your definition of full sun might differ a lot from mine.
4) It tastes like spinach.
5) I have no idea.
There, that was simple.
Now for a few more details: like all perennials it's tiny in its first year. Plant it in its final spot then, or in its second year.
It needs a trellis, and it can't get a grip on smooth bean poles (you can of course make those poles less smooth by adding some well-placed nails here and there). It will get enormous; 3 m tall is not even unusual. Add in that it branches profusely (at least, if given enough fertilizer), and make that trellis (or those bean poles) sturdy. Our poles were quite sturdy, and the whole thing still fell over in late summer. Having learned from that experience, we put in hay poles instead of bean poles the following spring; they're sturdy enough. The twine which ties the poles together at the top needs to be sturdy as well, though.
... you pick the leaf and boil it as you would spinach. The young leaf is tastiest, and it appears before anything else really happens in the garden - except for wild nettles, of course, which can be used like spinach, too. And I'm told that good king Henry is an early appearer, too, but I haven't grown that one, nor have I seen it in the show garden of the Finnish Useful Plant Society.