San Pedro?

[Shane]

I got about a half dozen sections of a cactus from my housemate (he got them from someone else, doesn't know what they are). They remind me of some San Pedros I saw for sale earlier this year, but that's just a guess. What should I look for to identify them vs other similar looking cacti?

[stefan m.]

Among the lines of it yeah. Color matches, spines and areoles match,stem matches. Though, its odd that youreusing corked or damaged specimens to propagate.

[Shane]

Though, its odd that youreusing corked or damaged specimens to propagate.

My housemate was the one who cut it up. They all were rotting actually, and none had roots. I cut the rot out and treated it with rooting hormone

Is propagating with corked cactus bad? I thought the brown spots were just something that appeared as cacti got older, not something unhealthy?

[stefan m.]

No, just slightly less successful if i recall.Not seen many people do it with the older bits rootless, only with younger stems. Have fun propagating them.

[Shane]

I'm not so sure it's San Pedro after all. It kind of looks like some sort of "Cereus peruvianus". Actually, I have seen pictures of both that look exactly like what I have. (Side note: there are a lot of unreliably identified pictures of "San Pedros" for sale or otherwise out there. S.P. is hallucinogenic, and people are selling similar looking cacti to people who don't know any better)

How can I tell the difference between these genera (Echinopsis and Cereus)?

[stefan m.]

It does most certainly not look like any member of cereus. https://i.ytimg.com/vi/JKdwWHfIeZo/maxresdefault.jpg
How to tell appart?
1-stems
trihocereus(not multi ribbed forms)- glauscent to bright green, plump and rounder ribs, smooth edges
cereus- thin ribs, darker green to darker glauscescnt, rougher and longer ribs,
2-flowers
trihocereus-fuzzy flowers
cereus -not fuzzy flowers
3-spines
trihocereus-orange and yellow to brown
cereus-dark to black,
4- cereus is hardier
herese another guy with a cereus that he thought was a trihocereus http://cactiguide.com/forum/viewtopic.php?f=3&t=39973

[Shane]

It does most certainly not look like any member of cereus. https://i.ytimg.com/vi/JKdwWHfIeZo/maxresdefault.jpg

That cross section picture really helps. I agree, it does not look like that at all.

How to tell appart?
1-stems
trihocereus(not multi ribbed forms)- glauscent to bright green, plump and rounder ribs, smooth edges
cereus- thin ribs, darker green to darker glauscescnt, rougher and longer ribs,
2-flowers
trihocereus-fuzzy flowers
cereus -not fuzzy flowers
3-spines
trihocereus-orange and yellow to brown
cereus-dark to black,
4- cereus is hardier
herese another guy with a cereus that he thought was a trihocereus viewtopic.php?f=3&t=39973

Good to know. Thanks for sharing