What kind of Column Cacti has 5

[welgoson]

I'm looking for help identifying a cacti that I brought back from Florida. Its mother was 15 feet tall with many arms and I believe yellow flowers.
I think it is a 'column' Cacti but my online searches have brought up various latin names and none that have 5 fins that give me a latin name. Most of the column cacti have 6 or more fins(are they called fins?).

I would like to know this Cactus origin, if it can survive freezing, and its latin name so I can get to know it better.

Please help if you can,
Thanks
Steve

[Kamos]

It looks like Cereus peruvianus to me. I think the ribs can vary from 4 to 6.
These are very hardy cactus.

[greenknight]

I agree, though that name is problematic - see: http://www.cactiguide.com/article/?article=article3.php" onclick="window.open(this.href);return false;

They're hardy, but plants growing in pots can't take as much freezing as those growing in the ground. You don't have to worry about a light frost when the plant is dry and dormant, but you don't want the root ball to freeze through. I lost one about 3 feet tall when the temperature unexpectedly dropped to 15 degrees F.

[welgoson]

Fascinating to learn about Cereus repandus and/or Cereus peruvianus. Good reading from the link in cactiguide. Still confused but only because it sounds like these species have mutated from human cultivation. So can we have new species? And I'm curious why his genus of cacti are not categorized by the quantity of its 'fins'.

From the variety of this species it seems it may be hardy enough to survive my North Carolina winter, though with some cover, at least for the root ball. Very encouraging, though I think I will wait through this winter for spring before planting it in the ground.

I wonder has there been any work on categorizing these species from a DNA perspective?

[Dixie Chicken]

Just a quick note about hardiness... I lost one like this, a 15 footer, last winter, when temps dipped below freezing for a few nights in a row, here in the Panhandle of Florida. It was planted out in a bed, protected from the north wind but not covered. It didn't take very long to figure out it was going squishy! Interesting to me was the 'skeleton' it left behind. Pipelike, but very hard wood, which explained why it was so sturdy in the wind! Good luck with this very nice plant.

[welgoson]

Thanks bunches for input on freezing. Doesn't sound promising to plant it in my zone. I'm on the edge of 7 and 8. Next Spring I will have no choice but to plant it if it grows any bigger, which of course it will. Maybe this subject is not allowed will arrive all at once.

[greenknight]

The number of ribs can vary, even on the same plant. The one I had started out with 5 ribs, but then started putting out growth with only 4 ribs.

[SnowFella]

Short of freezing them just about nothing can kill one of these!
I had one outdoors that fell over by it's own weight in February, chopped it into pieces as it was just to big to stand back up again and only kept one tip piece.
Since then it's sat un-rooted ontop a bench in the backyard, some new root nodules have appeared on the base but I just haven't got around to replanting it. Now with spring well on it's way it's after 8 months since I cut it up set buds and are about to flower.

[welgoson]

Thanks for the info on the ribs greenknight. Will change my terminology away from the fishy 'fins' term.

With the leads on latin naming I was looking up this catcus and it seems to be visually more of the family Cereus hildmannianus rather than what I've seen online for Cereus repandus, which seems to be a smaller species.

And then I was amazed at one cactus of Cereus hildmannianus of the supposed uruguayanus subspecies that looked more like the regular species.
http://davesgarden.com/guides/pf/showimage/358334/" onclick="window.open(this.href);return false;
Other pictures of the uruguayanus subspecies seemed to show more twisted stems.

It seems that there are photographic variations of how to differentiate these species. Goodness gracious there seems to be no standard I can find.
Its all quite interesting however.

[greenknight]

They're highly variable, they hybridize readily... what it "really" is it's hard to say.