Need Id for this cactus

[keithp2012]

Also why is the bottom like a balloon?

[ossy96]

It looks like echinopsis subdenudata, about the bottom im not sure maybe it was etiolated...

[DaveW]

Looks like it was originally hard grown then potted in a more nutritious soil and produced more vigorous new growth. However the new growth does not look etiolated being a nice dark green.

If some plants have been grown slowly, in order to blur the old growth into more vigorous new growth, you have to slowly alter their growing conditions. As it becomes larger though that old growth will be lost down at the base.

[keithp2012]

Looks like it was originally hard grown then potted in a more nutritious soil and produced more vigorous new growth. However the new growth does not look etiolated being a nice dark green.

If some plants have been grown slowly, in order to blur the old growth into more vigorous new growth, you have to slowly alter their growing conditions. As it becomes larger though that old growth will be lost down at the base.

Do you think it’s grafted onto another species? The bottom spines almost resemble peyote.

[DaveW]

Possible, but hard to tell from the picture. The base does have some spines the top does not. Grafting on Lophophora is not likely since most grafts are done on Cerei or Echinopsis to speed up growth. Trichocereus being a favourite hardy stock.

[Carpkel]

I have had some other species do this in my collection, also. I have suspected it was the way it went dormant, but never figured out the true reason behind it. Mine are grown outdoors in full sun and are under grow lights inside in the winter. They are kept dry in the winter

[Carpkel]

My theory is that when the older base of the cactus corked over, the corking was thick enough to prevent it from expanding from the new growth. Thus, it growing upward and outward like a mushroom head. Any opinions about that theory?

[Carpkel]

Another thought is that the growth point was damaged and the new pup/growth point that formed overtook the first in size. Although the cacti of mine that grew like this never damaged its main growth point or grew a new pup

[Kipody]

cool plant!
The same thing happened to my Lophophora seedlings
looks like a miniature version of your plant
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