The most attention-getting feature of the unknown plant I saw in Jamaica is the shape and colour of its fruit. They are numerous, roughly the size and shape of Bartlett pears except that there are 5 (sometimes only 4) stubby little "horns" growing from the stem (wide) end of the fruit. They are a beautiful bright, golden colour, very large compared to the small size of the shrubs. The clerk at the store where I bought the branch referred to it as "Foxface", but the only online reference I can find is about tropical fish. The fruit looks slightly like a giraffe head, with the pointed end for its muzzle and the stubs an excess of little horns. It has just occurred to me that they could be immature trees, because I only saw two of them in the two weeks I was in Jamaica. The outside bark is fine, slightly vertically ridged. The inside wood is very light in colour compared to the bark. None of the Jamaicans I asked knew what the plant was called, and none of them thought it was as strange as I did. Recently, I saw branches of the same fruit for sale at Granville Island Market. I brought a branch home and cut one of the strange fruits open to see what was inside - no flesh, only hundreds (thousands?) of tiny seeds. The two shrubs I saw were no more than 4 feet tall, with broad, vaguely grape-leaf shaped leaves. It was hard to tell if more than trunk was coming from the same plant, or if two or more plants were growing together.
Sounds like the plant in the thread Plant ID | UBC Botanical Garden Forums but with a different common name.