Sacha wrote:

It's a bit like going round a garden with a truly manic enthusiast and I do
love seeing other peoples' gardens! But in one public garden we go to
sometimes we used to almost dread seeing the past curator because we would
be there for hours, looking at virtually every leaf of every plant.

Ah the "See! - On this form the attenuation is 0.225mm. longer than
the more common variety, but the petiole is generally 0.316mm.
shorter" syndrome. Short of a using magnifying glass it is impossible
to see the difference and horticulturally, there's very little point
in differentiating the forms anyway. I'll never forget a desparately
hot and steamy day in the '70's being virtually dragged around a
botanical gardens by its hugely knowledgable, but desperately pedantic
curator. An utterly charming chap in many ways, but after 5 hours my
head was spinning. I never went again and tactfully avoided
responding to subsequent invitations.