Please I.D this cactus

[CactusMad]

Hello I am new here,I hope to be an active member and am extremely obsessed with cacti.I wonder if you knowledgeable people can clarify the identity of this cactus.I personally think it is a mammillaria geminispina but it is being sold as a mammillaria parkinsoni.Any and all help would be greatly appreciated.

What Cactus 2.JPG (64.83 KiB) Viewed 1187 times

What cactus.JPG (61.09 KiB) Viewed 1187 times

Thank you.

[teo]

Mammillaria geminispina

[CactusMad]

Thank you,I thought it was.I have told the seller before but they insist it is a Parkinsonii.So I thought i would ask on this forum.Thank you for the confirmation i appreciate it.

[teo]

Well, I have one just like this and I have labeled it geminispina. It should have two long central spines (as the name implies). Mine also have red/carmine flowers.

[DaveW]

Yes gemnispina means "twin spined", but whilst the original plant described must have been so I think the species is far more variable since I can only detect one long central on mine, which otherwise looks identical to yours above. Mammillaria noblis and a few other variants are now sunk into synonymy under gemnispina:-

http://www.cactus-art.biz/schede/MAMMIL ... ispina.htm" onclick="window.open(this.href);return false;

Mammillaria parkinsonii too is fairly variable as to spination:-

http://www.arkive.org/owls-eye-cactus/m ... rkinsonii/" onclick="window.open(this.href);return false;

http://www.photo-thorns.am/photogallery ... nsonii.htm" onclick="window.open(this.href);return false;

Of course the best way to tell them apart is flowers. As Teo says gemnispina has purplish-pink ones whereas parkinsonii's are small yellowish-white.

The problem as always is we get used to selected clones in cultivation being typical of the species, whereas in habitat they may be far more variable even within the same population.

[CactusMad]

Hi Dave and thank you for your input and help.What made me think straight away that it couldn't be Parkinsonii is because i always thought they only divided dichotomously and never had pups as this plant does.Is this a correct assumption or am i wrong?


Sylv.

[teo]

Here is my geminispina.

M. geminispina

DSC_1146-c.JPG (63.07 KiB) Viewed 1101 times

[DaveW]

Dichotomous branching is sometimes characteristic, but many cacti seem to be able to do it exceptionally. I have an Echinopsis (Pseudolobivia) that has done so, but that's uncommon. It is characteristic of a few Mammilaria's such as crucigera, parkinsonii etc. I can't recall ever seeing a dichotomous geminispina though.

http://davesgarden.com/guides/pf/showimage/37087/" onclick="window.open(this.href);return false;

http://mammillarias.net/gallery/mammill ... onii&lg=uk" onclick="window.open(this.href);return false;

http://mammillarias.net/gallery/mammill ... eminispina" onclick="window.open(this.href);return false; ssp geminispina&lg=uk

As to offsetting or pupping, again I think all cacti are capable of doing so but perhaps it's rarer in parkinsonii, but the one in the following link seems to have done so. However it is interesting to note that virtually all the "pupping" so called parkinsonii's in Google images have red flowers, therefore I am doubtful they are parkinsonii:-

http://davesgarden.com/guides/pf/showimage/118292/" onclick="window.open(this.href);return false;

http://davesgarden.com/guides/pf/showimage/164916/" onclick="window.open(this.href);return false;

[CactusMad]

Thank you everyone for all the info and help.I really do appreciate it.I am going to label mine Mammillaria geminispina.I havn't had it very long so it hasn't flowered yet.Will have to wait till next year to see what flowers it will have.

Sylv.

[DaveW]

I think your identification is more accurate than your nurseryman's Sylv, many of them simply sell plants under the names they originally got them as without later checking their accuracy.