In message , Mary Fisher
writes
It's a form of portulaca.

Oh - never heard of it :-)

So I Googled and came to this site which I think would gladden the
heart of every poster here! thinks for leading me to it.

http://www.microscopy-uk.org.uk/mag/...ww.microscopy-
uk.org.uk/mag/artapr04/bjrosemoss.html

Mary

When I was tiny my grandmother had a flight of wide steps leading up to
the house, and gaps had been left at the bottoms of the risers, and
portulaca were planted in all the gaps all the way up. I loved those
steps and what I called the "worm-flowers" (because of the shape of the
leaves)! She left the house when I was three, so it's one of my earliest
memories!

--
Klara, Gatwick basin