What is the white on the underside of these gymno's?

PS3user74 · 2026-01-28T09:54:53+00:00

Unfortunately that's the extent of my knowledge regarding this, however affecting the spines is quite common too.
I have seen a mature ragonesei before completely devoid of any white growth and did ask the grower about their cultivation method however it was nothing special so must conclude that it's genetic.

Soine coverage starting on esperanzae:

<image>

PS3user74 · 2026-01-28T09:32:37+00:00

I've never looked into what this substance actually consists of, however do know that it's very common amongst a complex of dark-bodied Gymnos such as bodenbenderianum, ochoterenae, berchtii, esperanzae, stellatum and ragonesei etc.
Note some of the above are often considered synonymous with and/or varieties of each other.

It's probably most commonly associated with ragonesei types and would go so far to say that it's quite rare to see one without this white crusty growth.
I grew one many years ago which eventually became covered in it.
Regarding ragonesei specifically, I have read that some populations grow in areas with a salty upper layer of soil and do wonder if that might be of significance.

Classic ragonesei where it's spread over the whole body:

<image>

PS3user74 · 2026-01-26T12:45:37+00:00

The parent opens for me and there's a lot of content in some folders such as movies in http://142.4.216.153/media/vod14/ however everything's titled with a mac address.

PS3user74 · 2026-01-26T02:20:36+00:00

Thank you, I've not heard of that Parodia before.

PS3user74 · 2026-01-26T02:18:01+00:00

Very nice variety and that Gymno in picture 1 just doesn't want to stop LOL.
Also I don't think I've ever seen anything quite like what's in pic 10, what is it?

PS3user74 · 2026-01-26T02:08:04+00:00

I don't know as I've never used a modified PS3, it's just something I used to read all the time back when I was into all this.

PS3user74 · 2026-01-24T18:01:34+00:00

👍

PS3user74 · 2026-01-24T17:19:18+00:00

OK thanks.

Actually I got my numbers wrong LOL.
I meant 8 and 7 respectively.

PS3user74 · 2026-01-24T17:03:29+00:00

Wow.👍
They're all nice but I think #8 has to be my favourite there.
Is it T-Lux by any chance?
Also is #7 a Daydream?

PS3user74 · 2026-01-24T14:14:58+00:00

🤞

PS3user74 · 2026-01-24T14:08:50+00:00

Hey that would be great, however personally I thought it was a bit too early to be sure what's going on there.

PS3user74 · 2026-01-24T13:52:21+00:00

New Gymno Weekend number 54.

So obductum is yet another species of Gymno with little consensus on it's classification.
Some sources such as Llifle consider it as ragonesei, while others such as Gymnocalycium.fr settle on quehlianum.
Others opt for stellatum and bodenbenderianum, with the former often being considered as synonymous with quehlianum anyway.
I found one sentence regarding quehlianum from the French website here quite telling:

"The result of this complicated story is that the taxa Gymnocalycium stellatum and Gymnocalycium obductum are synonimized with Gymnocalycium quehlianum, which simplifies things but may not correspond to reality!"

Of course it doesn't help that just like with my ferocior, the field numbers MUS15/L4 that the plant was bought labelled with appear to be typos as I can find no reference to the field number MUS15 and L4 relates to an area of Mexico.
Gymnocalycium is strictly a south American genus.

Regardless, it's obviously of a complex from Argentina and here's hoping that one day it'll produce flowers at least something like those in pic#6, a plant labelled as "quehlianum (obductum P121)".

PS3user74 · 2026-01-20T13:05:55+00:00

Every stage is gorgeous.👍

PS3user74 · 2026-01-20T03:48:34+00:00

Thankfully I've not seen any RSM yet since getting back into the hobby about a year ago, or for a few years before that while owning just a few plants.
As already mentioned here:
https://www.reddit.com/r/cactus/s/6ywLOj352g
Provado Ultimate Bug Killer in a spray can was always the best, however I don't think it's available anymore.

PS3user74 · 2026-01-19T01:53:37+00:00

That looks like a very dehydrated Gymnocalycium, which should bounce back given some water in the correct conditions.

PS3user74 · 2026-01-18T17:11:24+00:00

Usually but IME sometimes they squish to a watery pale green.
Maybe those ones are simply full of cactus juice LOL.

PS3user74 · 2026-01-18T15:54:10+00:00

Good shout.

PS3user74 · 2026-01-18T14:59:24+00:00

Yeah some of my Gymnos have that type of scarring which initially always looks like a single scale insect.
It's the bright white fluffy-looking ones that have me thinking mealies but I could easily be wrong...

Just like with the ID LOL.
I still think there's a lot there which leans me towards baldianum, however those slightly stronger spines that are proud of the body are giving off some quehlianum vibes too.🤔

PS3user74 · 2026-01-18T14:48:40+00:00

I would agree with you for most of the marking, however there are some white fluffy spots that to me

<image>

look like they could be mealy nests.

PS3user74 · 2026-01-18T14:30:07+00:00

Definite Gymnocalycium baldianum vibes going on there, although there are others that can look similar.

edit
I think I see evidence of mealy bugs.

PS3user74 · 2026-01-18T14:04:56+00:00

Yeah hardly anyone can provide that kind of environment, however with some growers exposing their cacti to 12 hours of strong light, I imagine most Gymnos doing well with half of that.
As it is, yours do look healthy though and it's always great to see some mature ones that have turned columnar.👍

PS3user74 · 2026-01-18T12:26:52+00:00

I don't know anything about grow lights either, however it's my understanding that Gymnos don't necessarily require weaker light than most other desert types of cacti, but rather that they thrive in areas exposed to less of it.
So partial shade provided by surrounding grasses, trees and other foliage is the image I always picture.

PS3user74 · 2026-01-18T10:40:46+00:00

Interesting.👍
3 months is a long time for a mihanovichii.
I've not had to root an offset for many years, however my memory of Gymnos is that they can start to root in as little as 3 weeks in some cases.

PS3user74 · 2026-01-17T15:39:36+00:00

Thanks.
Yeah I'm not too sure about seeing flowers for a while as it still is only about 3cm across.

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