I've heard of Tree Spinach, Chaya
grows easily from cuttings, leaves year-round
doesn't taste quite like spinach, and is high in oxalates, so cook it well.
I could give you cuttings, but I'm on the BI

Here is a link that might be useful: wikipedia tree spinach

Yes, the purple "tree" collard or "walking stick" kale is Brassica oleracea var. acephala. It has no oxalic acid. After reading this link, http://treecollards.blogspot.com/I realize that it might be a more accurate description if we called it a "headless cabbage tree" or a "walking stick cabbage," because it's more of a cabbage.

A lot of people order the cuttings from California: Tree Collard Cuttings from Bountiful Gardens. Apparently Annie's Annuals in N. California is now also selling plants.

But I got mine on craigslist from someone who already grew the cutting.

Here is a good search methodology on CL. Go to the "for sale" section of your local craigslist and cut and paste: " collard|brassica collard|acephala|tree" It should pull up any ads for tree collards. The little line is like an "EITHER/OR" in search terms.

If you are interested in perennial greens, here is another search term setup for craigslist: "alba|procumbens|Longevity|Malabar spinach|basella|gynura." It will search for longevity spinach and malabar spinach.

This site has more information on pruning and care: http://richardsfarms.vpweb.com/Tree-Collard-Information.html