Hi Dave... Ya know... this cactus has Many different names it goes by, but Opuntia argentiniana isn't a correct name, but that's the only one that comes up with pics of the correct cactus. What I mean is, the names this plant usually goes by is one of the many I listed above (plus many more I didn't list) and O. argentiniana isn't one of them... O. argentiana isn't either... It's O. argentina. Here's a list from Desert-Tropicals: Synonym: Brasiliopuntia argentina, Brasiliopuntia brasiliensis ssp. subacarpa, Brasiliopuntia subacarpa, Opuntia neoargentina, Brasiliopuntia neoargentina, Brasiliopuntia schulzii, Opuntia schulzii, Opuntia bahiensis, Opuntia argentina, Opuntia brasiliensis, Cactus brasiliensis, Brasiliopuntia bahiensis BUT... When I searched for the spelling you provided, Only Four links come up for a cactus by that name and two are either not about cactus or doesn't show an image. One was for a company that sells Flats of cactus with one listed as O. argentiniana and THAT appears to be the Mystery Cactus!!! The Other is from someone that Posted a thread Right Here on Garden Web, asking what the cute little cactus she had, that grew into a Monster is called! She even posted a picture! So, the cute little plant I've seen in planters, doesn't stay little. It must be a seedling... because the O. argentina cuttings I've seen look the same but are HUGE. That's why I suggested them. THANKS SO MUCH!!!! I had a feeling that's what it was, but without any confirmation or pictures or name to go with it, I couldn't be sure! Thanks again Dave. Mystery Solved! That didn't take long! :-) I love this forum!

Yeah it's new but I'm giving it a lot more light than the Lowes I bought it from did. I'll try to do some more searching. edit: I found a few things that mentioned there are some tall pachyveria hybrids that aren't actually victims of etiolation but just happen to be tall. I will admit it's leaves are quite fragile though. I may update this as time goes on

oof, nice one, NL. You're basically going to try re-rooting the rosette so I recommend sifting the fine particles from your substrate. Then replant in as small a pot as you can get (yes, smaller than the one you are using). The key is to be able to allow the moisture to evaporate quickly when you water. Watering, in this case, should be shallow and but frequent. For faster results, make sure it gets warm during the day (20C-25C) but cold at night (10C to 16C). It's the difference that is important. I do this by putting rooting haworthias right against my pathetically insulated glass doors that should really be replaced by now. But you get the idea. Another technique is to just water the pot then sit it on cotton cloth so the excess moisture can be wicked out. I find there is less room for error this way though; but you might find it easier yourself. Fresh roots look like this: That white bit is the active root, if your plant has those, you will need to target that small nub when you water. If over-watered, that growing root will melt and the plant has to start over. The longer roots in this photo are old ones that are about to whither and are no longer moving water from the substrate to the plant which is why this one was dehydrated. Remember, haworthias are very slow plants. This can take weeks to months.

The plot thickens! Something instinctively told me it didn't seem like the other Morus seedlings I'd seen, but I admit I gave absolutely zilch thought to alternate vs. opposite. There is a Hydrangea 'Honeycomb' about 6 feet away. Now I'm wondering, could it just be a very distant sucker!? I've never seen a Hydrangea sucker anywhere near that far, but, OTOH, I have more far experience with mopheads than H. paniculata...'Honeycomb' is the only PG I've grown at all. OTOH if it is a seedling, it is 100% a first time occurrence for me. NEVER seen Hydrangeas self seeding in my garden. I wouldn't have even considered that, but, now that I think about it, it could make sense I suppose. Floral do mopheads self-sow in the mild climate of SW UK? They certainly do in the Azores LOL. So far my most 'aggressive' ornamental self seeder is...drumroll please...camellias. Now I think I'll dig it up tomorrow to see if it's attached to 'Honeycomb', if not, plant it somewhere else. No harm in seeing if it has some desirable trait.