You may be describing Hylocereus, which is an epiphytic cactus with white blooms, not sure off the top of my head if they're diurnal but I'm sure Google would know.

Thanks but the Hylocereus is night blooming according to the references on google so I need another lead.

Is this what you are looking for?? This is my Epiphyllum(sp),i also have it in pink ,and i bought some more cuttings this spring that i don't know the colors of yet,i'm hoping i have a yellow one!! Time will tell.
Kathi

{{gwi:515636}}

I believe that's the one. Your photo is upclose and the one I saw was at a distance and in a hanging basket. Since I posted the other day, I found one at a nursery and he said it was the mini white - whatever that means. Kathi where did you buy your cuttings? Thanks for the photo.
Pat

Try epiforums - all sorts of epi info, trading etc...if you can't find it there, it doesn't exist!

I signed in and evidently they didn't get back to me with an email or whatever they do and I can't post or download anything. I've emailed them so maybe they
will do what they have to do to help me. Thanks,
Pat

Epiphyllums bloom in the day and are sisters to the night bloomers, althought day bloomers come in many colors and are pretty, night bloomers have that wonderful fragrance that you just die for. I collect Brugmansias aka "angels trumpets" for that very purpose, at night you can smell the flowers within 100 feet of the plant, its wonderful!

There are white epiphyllum hybrids. Check out some of the online vendors.

Dave
Milwaukee

There are white day blooming hybrid epies. I think the one that looks like picture above is called Young Nun, it has some fragrance too. Try google Epies by Pat. I bought from her few times, good seller and nice size cuttings. She might have some other white day blooming epies.

Thanks everyone for all of the information and I feel more confident now. I got a catalog from Epiphyllum World the other day and there are so many epis to choose from. I just hate having to do a $20 minimun order plus shipping to begin with but I might break down and do it.
Pat

True/species epis are night flowering. Day flowering are hybrids & are usually more colorful.
I did not see his prices but Bob Smoley may be cheaper. He has feedback of being late sending for some people, however.

Thank you.