OK here is the picture
{{gwi:516177}}

I have a plant that looks like your called Monkey's Tail, Dog cactus is listed as Gramham's Grusonia grahamii but the picture doesn't match. I used Edwqard Anderson book as my reference. Most of this species had yellow flowers, but no picuture shown of the 'Dog Cactus' Sorry I don't think I did well. Norma

Dog tail is also Deamia testudo, it's been so long since I've had one though to be sure that's your plant. It's not Aporocactus flagelliformis, I'm pretty sure.

I agree with mentha, it is not an Aporocactus flagelliformis. Your cactus is common in flower shops etc., but I have not yet seen it reliably identified. The best guesses I have found is some kind of Selenicereus, maybe the previously mentioned S. testudo (old name Deamia testudo).

I agree you have the Deamia testudo....I have one just like it, but unfortunately mine has NEVER bloomed.

Yours looks a heck of a lot better than mine, too.(Ã)
Mine is quite an 'ugly' plant...with many aerial roots.

I had one of these years ago... it was my favorite cactus... the spines never came out in my hand! But from what I have found, while searching for Selenicereus testudo, are images of what I think is the Mature form of this plant. I think the one most people have in pots is an immature or juvenile form. Maybe potsize has something to do with preventing it from maturing? So, if it's just a juvenile form, there won't be any flowers produced.
So, has someone started marketing this plant again, I haven't seen it on the market for quite some time.
ks-girl, where did you buy it? Feel like trading a few pieces? I can send you a few pieces of Cleistocactus winteri, which looks similar to but thicker than Aporacactus flagelliformis.

Thanks everyone for all your help.
There does seem to be a bit of a mistery around this one.
It seems most people think it may be Selenicereus testudo any other ideas out there.
I know it's not aporocactus flagelliformis or cleostocactus winteri since I have both of these and they are differant.
I found it at a Lowe's last week and I saw one at another Lowe's last fall. They're grown by Exotic Angel and they're very bad at getting names correct on their plants.

Looks like Aporocactus flagelliformis, common name, Rat Tail Cactus.
They're lovly cactus, hang to the ground, and their big, red flowers are stunning, especially when grouped.
KS-Girl, Google 'rat tail cactus' or 'rat tail cactus pictures'. You'll see what I mean..Toni

ALtman's also markets this plant here on the West coast. You usually see it late spring on into fall.

Toni, I have both the pink and red Aporocactus flagelliformis (Rat Tail) and they're differant, they have smaller and more rounded stems. Mine is budding now.

Your plant is definitely a dogtail cactus. I have been looking for one myself and they are very hard to find in Ohio. My last one was stolen from my porch. I am very familiar with this plant and recognized it the minute I saw your picture.