|Can you see where it got its name? Picture from Wikipedia|
Technically it's the Medlar (Mespilus germanica), which ticks every box for being a European native with a long British history, a really weird fruit tree, and possessing a filthy folklore. "Open-arse" was its original folk name.
It was really common and really popular back in the Middle Ages, as medlar fruits were some of the few available to consume during winter. That's because you can eat them only after they've started to decay.
|Yummy! (pic from Wikipedia)|
Due to its strange appearance and pungent squishiness, medlar fruit was associated with the female genitals - and also became a metaphor for premature decay, as in the Prologue of Chaucer's The Reeve's Tale:
By his time the word "Medlar" had become specifically a symbol and slang term for a prostitute: sweet and desirable but 'rotten on the inside' and old before her time.
Lucio. I was once before him for getting a wench with child.
Duke. Did you such a thing?
Lucio. Yes, marry, did I; but I was fain to forswear it: they would else have married me to the rotten medlar.
(Measure for Measure)
The misogyny reaches its succinct apex in The Honest Whore by Thomas Dekker: