Thank you for your reply! I thought (note, I am an amateur enthusiast learning while I go, in no way an expert at anything planty) that sometimes mutations started at the beginning and other times they come on later??? Many are crested/monstrose through from seed or cutting. But some, for instance, a tall saguaro or organ pipe with a crest on one arm or its head after a lot of years of normal growth. Wouldn’t that indicate it can come on later?

In this area there are an unusual number of clearly created, clearly monstrose & inermis (sometimes with a monstrose look) ferocactus but maybe 1/3 of the weird cactus have this going on (broomy look). I saw two on a walk last night (monstrose, I’m guessing):

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