This might be a rather silly question, but it's been annoying me for years.
My great-uncle had an apple orchard in northern Vermont in the 1960's, around the Burlington area. Half was planted with Mackintosh, the other half was a variety I can't remember. The fruit was green and sour enough to make your mouth pucker, about the same size as the Macs, and ripened about the same time as the Macs, but not quite as juicy. They were quite likely destined for cooking rather than eating, as most people don't like them that sour
For some reason, the name Wintergreens comes to mind. Could that be right?
I really wish I could find out what the variety is, as I like super-sour apples (with salt). Any time I ask about sour apples, people suggest Granny Smiths, which to me are fairly sweet.
I've tried asking various apple growing communities, but never got any answers. Any of the relatives who might have known are long gone now.