Possibly four o'clock, aka mirabilib, marvel of peru.

http://aggie-horticulture.tamu.edu/e...3/art7jul.html


wrote in message
ups.com...
A friend gave me a plant which produces many yellow single cup shaped
flowers at every sunset .
The flowers fade very quickly lasting only one night but they are
replaced with a new crop at every sunset. I live in the North East of
England.
Can anybody tell me the name of this plant please?
Thank you
Tom