Maybe an Opuntia that's trying to be crested but not quite getting there.

@mcvansoest, any thoughts?

That is the first thing that came to mind too. The spines really remind of an Opuntia I see for sale regularly but I can never remember the name of.

However, there appears to be some sort of structure that reminds me of ribs... so at second thought I am thinking some kind of crested non Opuntia cactus, but even harder to pin that down unless you had a similar one with an ID tag. It is pretty spectacularly crested.

Thanks for the feedback. It's at a brand new small nursery/venue in a residential backyard across the street that's only open on Sundays. Opuntia was my initial first thought too. The owner doesn't know it. I'll be keeping an eye on it and may update the photo/thread here in a year or so.

Whatever it is, it sure is interesting.

Here's a current photo with flower and new cylindrical/normal growth.

Its a type of Cleistocactus growing crested. Very cool!

I can't tell if it's a Schwarzenshrub, or a Popeye.

I always though Popeye was the common name for a sweet potato plant (I yam what I yam) so it must be a Schwarzenshrub.

Isnt this cylindropuntia fulgida cristata

Not with that flower and the one reverted arm.

I agree with Daisy. The flower is the definitive indication that it is a crested Cleistocactus.

Didnt see that one