mulberry bush

[neil]

I'm aware (in the UK) of the gooseberry bush (under) as source of babies
when answering inquisitive children, but where does the mulberry bush
originate?

I know the children's rhyme 'Here we go round the mulberry bush', but the
citation below implies that a mulberry bush is the source of illegitimate
offspring. Am I correct, and is it American?

"She says she's been married but Carolyn [...]. These artist types, well.
[...] Even if she did have the kid under a mulberry bush, it doesn't make
him any the less of a good kid, right?"
--Katherine V. Forrest, 'An emergence of green', Silver Moon Books, London,
1990, 128

--Neil Crawford