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 ...

C. haseltoniana usually has yellowish/orange wool in the crown or areoles. As said previously it is hard to identify Copiapoa's whilst small.

http://www.llifle.com/Encyclopedia/CACT ... seltoniana

Maybe somebody who grows many from seed can help?

The problem is Copiapoa's as young plants often look quite different to an older plant. http://www.llifle.com/Encyclopedia/CACTI/Family/Cactaceae/1380/Copiapoa_cinerea#:~:text=Description%3A%20Copiapoa%20cinerea%20is%20one%20of%20the%20most,solitary%2C%20or%20slowly%20offsetting%2C%20globular%20to%2...

See:-

https://cactus-moravia.eu/other-news/py ... ak-sp-nov/

Some tuberous rooted cacti that grow among or under rocks or even shrubs have ev0lved an extreme form of etiolation to get their flowering heads above rocks etc for pollination. This modification is retained even if grown in pots when no rocks are present. https://bcss.org.uk/turbinicarpus-subterran...

I presume you are aware of these articles? https://link.springer.com/article/10.1007/s00442-007-0698-y https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0081513 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2701848/ https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2745...

Just give me the usual picture credit and you can use what you want.

DaveW (Dave Whiteley)

Latest edition of free to download Cactus & Succulent Review is available here:-

https://www.cactusandsucculentreview.org.uk/

You can use any of my pictures I posted on my BCSS Travelogue. The later ones are habitat photos.

https://www.forum.bcss.org.uk/viewtopic.php?t=164681

Rarity is often a matter of opinion and can vary county to country depending what's freely available in that country. Also some species are more desirable to collectors than others, therefore a not very attractive species may in fact be quite rare but there is not a widespread market for it. Take fo...

The crown is etiolated through growing in too low light. The centre should have similar spination to the sides. If kept in good light it should improve.

Latest edition of free to download Cactus Explorer is now available, plus all back issues.

https://www.cactusexplorers.org.uk/journal1.htm

Incidentally Ossy the easy way to tell a Gymnocalycium apart from many other genera is neither the buds, flower tube or fruits have any hairs or bristles on them like your Notocactus (Parodia) does. "The genus name Gymnocalycium (from Greek, "naked calyx") refers to the flower buds be...

Agree with Nino, but probably the longest spined form of Parodia (Notocactus) mammulosa known an N. turecekianus. https://www.cactus-art.biz/schede/NOTOCACTUS/Notocactus_turecekianus/Notocactus_turecekianus/Notocactus_turecekianus.htm Notocactus mammulosus used to be split into three different speci...

As Spence says any blue in cacti is caused by the scattering of light and not true blue pigmentation. Cacti cannot have true blue flowers either. The only apparently blue flower = Wittia (Psudorhipsalis) amazonica is caused by its textured surface scattering light as in Morpho butterflies wings and ...