Someone brought in this plant which they referred to as a Crown of Thorns. It is clearly a Euphorbia but not E. milii. There are no thorns, but some fuzzy growth along the ribs of the stem, which is four sided, the leaves are appr. 5 inches in length, and the petioles are a bright red.

I know there are appr. a zillion Euphorbias out there but I thought I'd toss it out there....
in advance!

I've found a couple of references, the first one has a long discussion about this plant but they didn't seem to know what it was, scroll to the bottom.

http://plantsarethestrangestpe...

I found it on a Russian site so had to copy the address and translate the page ..

http://translate.google.co.uk/...

There's two Euphorbias mentioned which are similar, Euphorbia leuconeura and Euphorbia lophogona.

This looks like Euphorbia leuconeura.

https://www.google.co.uk/searc...

Euphorbia (Euphorbia lophogona)
Madagascar Jewel (Euphorbia leuconeura)

Spot on for E. leuconeura; thanks so much!