I've been trying to get a picture of these huge flowers for about 5 years, but always forget to sneak out in the dead of night to look for the opened flowers. In the morning they will be dead. This is Hylocereus sp (aka dragon fruit) growing on the large old frangipani tree in Tai Peng village. They are about a foot across. There were two open tonight. I saw them at around 12.30 - I'm not sure how long after dark they open.

<a href="http://s927.photobucket.com/albums/ad111/pchchch/?action=view¤t=Hylocereus3.jpg" target="_blank"><img src="http://i927.photobucket.com/albums/ad111/pchchch/Hylocereus3.jpg" border="0" alt="Photobucket"></a>

<a href="http://s927.photobucket.com/albums/ad111/pchchch/?action=view¤t=Hylocereus2.jpg" target="_blank"><img src="http://i927.photobucket.com/albums/ad111/pchchch/Hylocereus2.jpg" border="0" alt="Photobucket"></a>

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nice images! sometimes if you go out early enough in the a.m. they are still blooming. apparently you can use them for a tea, or a soup with lean pork

Zep, do you know if they are pollinated by bats or perhaps very large moths?

http://www.gardenguides.com/91723-night ... actus.html

I think the Googlemeister has got it about right, although the article he cites is about a different species of night-flowering cactus, Cereus greggii from the Arizona desert. The ones in Tai Peng look more like dragon fruit, Hylocereus undatus, which probably originated in that part of the world too (or at least in Central America), but are now grown all over the tropics, notably in Hawai’i and Vietnam. There are a lot of different cultivated varieties, so I don’t know which one this is. Looking up articles about dragon fruit, I see that both bats and insects are given as likely pollinators. Here in HK, though, I don’t know what the situation is, and I have never actually seen a fruit growing from the flowers. The owner of the cactus cut the flowers off in the morning for some reason, maybe to eat?

Yes, but that was the only ref I found that described how they were pollinated. I assumed related species are similar.

It was a bit surprising to me that cactus could grow in wet tropical areas like here.

There's a bit about it here

http://hylocereusundatus.com/