We’re all familiar with the greengrocer’s apostrophe.
The question is, what happens when you want to refer to more than one of the little bleeders?
First of all, we have to do a little old-fashioned parsing.
Is the greengrocer’s apostrophe an actual apostrophe belonging to an actual greengrocer?
No. While the apostrophe is a literal apostrophe, the greengrocer is figurative. Like the curate’s egg.
In fact you are just as likely to see a greengrocer’s apostrophe emanating from a large corporation or municipal authority as you are from a real live fruit and veg merchant.
All of which means that in this compound noun, greengrocer’s is an adjectival particle not a possessive. We are not asking whose apostrophe is it, but what kind of apostrophe is it? And there’s our answer. Because you don’t change the form of an adjective when making a plural out of the noun it qualifies.
So it follows that if you see several examples of the greengrocer’s apostrophe you have greengrocer’s apostrophes.
UNLESS you have walked past three greengrocers’ shops and seen the heinous punctuation error outside each one.
Then you would have seen three greengrocers’ greengrocer’s apostrophes.