Identifying a rebutia

[Phil_SK]

Well, apart from those Eriosyce villosa flowers I posted in the ?The way is barred? thread that couldn?t open for the spines, I?ve not had any flowers until this weekend. As you can imagine, I?ve been quite envious of all those Turbinicarpus and Rebutia pics that have been posted, among others. My first flower is on a Rebutia with a dubious ID and I?m hoping the flower might help solve the puzzle.
The plant came from Cactology last year, from John?s personal collection, and was labelled ?as R. ithyacantha Lau 350 + orange fl !!? Then on the reverse is written ?Rebutia leucanthema?? As I normally do when I get new plants with field numbers, I checked L350 in Ralph?s database where Aylostera ithyacantha is returned.
Plugging ?ithyacantha? into the International Plant Names Index gives the original Mediolobivia ithyacantha and a transfer to Rebutia (no Aylostera seems to have been validly published). Cardenas?s description is dated 1970, Lau?s collection is dated 12/3/1970 (although I appreciate the name would probably have been applied to his collection months/years afterwards).
Here?s my plant, anyway:
[img]http://i65.photobucket.com/albums/h233/ ... 6_3636.jpg[/img] [img]http://i65.photobucket.com/albums/h233/ ... 6_3637.jpg[/img] [img]http://i65.photobucket.com/albums/h233/ ... 6_3649.jpg[/img] [img]http://i65.photobucket.com/albums/h233/ ... 6_3638.jpg[/img] [img]http://i65.photobucket.com/albums/h233/ ... 6_3650.jpg[/img]

Modern treatments from Ritter, Pilbeam and the NCL treat ithyacantha as a variant of R. fiebrigii, which my plant isn?t. Searching the internet returns pictures of plants like fiebrigii, rather than like mine - like those here and here and those at the bottom of this page (why is it that all the interesting webpages I keep finding are in Czech?)

Any suggestions as to what mine might be? The body looks more R. ritteri or pygmaea -ish to me.
Incidentally, I expect the plant Hob posted in his ?Rebutia? thread (post 1, pic 6) is a cutting or seedling from mine.

[Hob]

Phil that looks just like Rebutia leucanthema in Pilbeams book apart from the pink flowers however he does go on to say that it "occurs rarely with pink flowers"

if you check the spines on my Rebutia leucanthema you will see they are totally different, which leads me to believe i was given the wrong name with my (free) plant from cactology.

this is the pic on the cactology website

cactology

[Phil_SK]

Hadn't thought to look if John had a photo of it under R. leucanthema! His ID has a question mark after it, which suggests it's one he's tentatively IDed himself from books or original descriptions.
I'd say your plant easily falls within the same species as mine. I don't have the Pilbeam book so can't comment on his photo. If you look at some of the photos of my plant the spines on the sides are rather longer than near the apex, so I'm sure the plant you were 'sold' is the same as mine. Whether it's leucanthema (=pygmaea now) was my only concern.

It's only since I've made that first post that I've searched properly for R. leucanthema. Many of the hits I'm getting associate it with the Rausch collection number 305. It's just possible that R305 could become L350 as the plant got passed around from collector to collector before it was given a name. Just goes to reinforce the importance of careful labelling and record keeping! I think I'll go with R. pygmaea 'leucanthema' without any field number to be on the safe side.

[Hob]

Pilbeam lists it as subgenus mediolobivia with the field number WR305

he mentions that CITES checklist has it as lobivia atrovirens

he makes no mention of it coming under the pygmaea umbrella though ?

[ralphrmartin]

Well, this plant pretty clearly belongs to the Mediolobivia subgenus (which includes pygmaea and leucanthema). In my opinion, there are not enough species recognised here. On one hill in Bolivia, I saw 3 populations growing within a 100 sq metre area with red, pink and yellow flowers. There was no hybridisation going on that I could see (the body forms were all subtly different, and the bodies consistently matched the flowers; there were no intermediates in flower or body present).

Basically, there are many small, widely separated populations, each on a different hill. Each has evolved to more or less in isolation.

Anyway, as to your plant: its close to what usually gets called leucanthma, and if you must give it a name, this is about the best shot. R. pygmaea v. eos is another name used for plants rather like this - but the picture of that in John Pilbeam's book is a rather odd looking plant, which is not what one usually see under that name.
There's a picture here
http://images.google.com/imgres?imgurl= ... n%26sa%3DN
whose flower is not too dissimilar to yours, although your plant seems to have less pronounced ribs.

[David_L]

I think this is closer to R. pygmaea v. eos than to leucanthema. It looks very much like a rather battered old stock plant I got from Cactology earlier this year under the "eos" name. It needs a bit of TLC and is not showing signs of buds as yet. I agree with Ralph about the variability of the Mediolobivia group. There are loads of deserving unnamed forms from the pygmaea complex collected by people like Mats Winberg and Ralph Hillman that should be better known and are available as seed. Ralph Martin is doing a great job of growing some of them up and offering them. Incidentally I challenged John Pilbeam about the strange "eos" flower in his Rebutia book and he agree it was an unfortunate choice of illustration which has rather haunted him. The plant in the picture subsequently died and he has never obtained another with the same prominent petal stripe.

[Hob]

interesting Ralph again in Pilbeams book v.eos shows CITES checklist has it as lobivia atrovirens but the two images are similar plants with different flowers........maybe just a poor image ??

[ralphrmartin]

Rausch considered the Mediolobivias to be Lobivias in his Lobivia 89 book, and you can see some good pictures in there of various plants.

Rebutia atrovirens is another "variable species" of Mediolobivia, and there are some plants which are pretty hard to assign one way or another to pygmaea versus atrovirens. Genrally speaking, I think of pygmaea types as being (i) cylindrical rather than spherical, especially in cultivation, and (ii) generally tending to have their tubercules in distinct rows tending to ribs. However, not all plants fit into such neat pigeonholes...