Thanks everyone and especially Tropicdude for the pics - very helpful to know what you should be looking out for. Does anyone know the name of the very small green round fruit on the end of a long whippy stalk that is sold in bunches like bouquets - it has a shell and large seed?
Hiyas Caz
As others mentioned, they are called "Limoncillos" (Melicoccus bijugatus)
They are called many things outside the D.R. ( Spanish Lime, Mamoncillo , Genip).
You do have to be careful "eating" these, as the slippery seed can easily be swallowed by accident and get lodged in your throat.