"Willow" wrote in message
...
Should probably add that I've only ever seen it with a single flower on
the
spike

--

There's a plant I've seen everywhere, particularly in areas that receive
little extra water & care (I've often seen them planted on council
verges
or
on islands in the middle of the road) but receive full sun throughout
most
of the Summer. It's a reedy plant, it might be a Yucca, the lilly/orchid
like flowers are on long stems, the petals of which are white with some
black & yellow bits (stripes or dots?) & a purple tounge...

I don't have a camera available unfortunately otherwise I would take a
piccie!

--
Wanda
aka Willow

It could be Dietes Bicolor aka Morea Bicolor... your description doesn't
match perfectly but is the closest match I can think of. Dietes also comes
in a pale blue variety which I have seen, and a lot of the online references
seem to indicate there is a white variety, which I have never personally
seen, and suspect they are confusing with the pale blue variety.