It looks vaguely like some sort of Euphorbia - like E griffithii maybe. are you able to take another shot with something to put it in perspective as to size, and if you removed a leaf, is there any white latex-like sap?

Maybe Euphorbia but not griffithii. It doesn't have those regular whorls. Leaves are alternate up the stem.

Looks like Euphorbia to me also; the leaves have that slight opacity which I credit to latex sap.

It is not a Euphorbia. I just posted another picture. The leaves when cut do not produce that milky sap, and the leaves are thin and soft.