Oh, crud. I apologize for posting this in the wrong forum. Is there a way to move this post to the right place?

1. Mammilaria
2. Haworthia
3. Parodia magnifica
Harry

First one looks like a Mammillaria. Possibly one of the M. vetula subspecies. M. vetula ssp lacostei? The picture is just blurred enough to throw me off, does the plant has any wool or bristles?

Are you sure those white stalks don't belong to the "Aloe", which I think may be a Haworthia. Does it have little white doughnuts on the leaves?

I think the third is Parodia magnifica, not positive though.

Ah, thank you! I think the second one is a Haworthia attenuata.
Parodia magnifica sounds good to me as well.
As for the wool or bristles question, I'm not sure. I took a few more pictures that I hope will help, but I'm sorry, my camera is just awful:
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Each little "finger" has four or so red barbs with a curve to them, and a dozen or so white straight whiskery barbs.

That shot and your description seems like Mammillaria crinita. Subspecies wildii is a common highly clustering form. A very similar species sometimes considered a subspecies of M. crinita is M. zeilmanniana. Flowers would give good clues for a more positive ID.

Hm. I'm looking at pictures of M. crinita but they seem somehow yellower where mine is reddish...and they seem much bigger. Hang on, let me take an overall picture for scale...

Here's one where you can see the size. That's a four-inch (10 cm) pot it's in. The squares on the cutting mat it's sitting on are one inch (2.54 cm).
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Overhead shot.
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The big difference between what I have and the pictures I've been looking at at mammillarias.net seems to be the shape of the (sorry, I know the correct terminology would help here) "thingies" to which the red and white barbs are attached.

To pick a random example, on the plant at the link below, the "thingies" are dark green and kind of a full conical shape.

The "thingies" on mine are much longer and more fingery. Like a cow's udder.

It is very very possible that mine has just not been treated as ideally as the gorgeous specimens at this website. I am trying to give my plants what they want, hence today's search for ID, but it's very possible that they are stunted in some way. When I first got this plant, the puffball shape in the picture above was totally absent; the clumps of growth were long fingers instead of compact balls. I'm not sure which is the optimal shape. (The "thingies" were still udder-like, though.)

I am going to try to optimize the poor thing's conditions and hope for a flower someday. This is why I'm so grateful for all of these clues to its identity!

Here is a link that might be useful: dark green

Binki, you're a natural for identifying Mammillarias. You have keyed in on the important things to be looking at, although I don't think "udder shaped" is the correct technical term ;)

The thingies are called tubercles. Their shape is one of the factors that can be used to ID a species. The things to look at are whether the tubercles have corners, how many sides they might have, whether they are evenly shaped or have a distinct keel, whether they are conical or cylindrical, truncated or tapering to a point, widely or closely spaced, short or long, and whether the shape of the base remains round or changes to a square shape to fit with neighbouring tubercles. Some of these factors can change a little with the growth pattern. For example, a very well watered cylindrical tubercle may bulge at the tip.

The overall shape of the plant is also somewhat important. Massively clustering plants like your's would normally mean one of a handful of species, but it could also be an extremely old specimen of quite a few others. The first one to look at would always be M. prolifera but the spines don't match. Another very common clustering species is M. elongata but again not a good match for your's.

Possible the most important factor for an ID is the number and type of spines. You describe your's as having about four reddish central spines, curved (and one hooked?) and about twelve fine white radials. That alone, given that it is a mature plant, would be enough to tie down an ID to a very small number of species. The most common plant matching that is M. zeilmanniana.

The size and shape of the individual heads is also important. Now it seems that these are less than an inch across. You describe them as being finger shaped when you got the plant, but they are now more globular. The M. crinita ssp wildii which I suggested before would have heads closer to two inches across. That's really quite small. A small clustering plant to look at would be M. glochidiata.

Care for any of these species is much the same. Full sun or just a little afternoon shade, regular water in summer but with very good drainage so the soil doesn't stay wet, little or no water in winter, keep fairly cool in winter but no frost. The only reasons I can think that your plant wouldn't be flowering is lack of a chill last winter or lack of sun this summer. Adapt slowly to the sun if it is kept in the shade now.

Wow, ok, this is good. You are right that only one of the reddish central spines is hooked; the other three are pretty much straight. The white radials are smaller and finer than the spines. and very delicate. Maybe it's because it's an indoor plant?

The tubercules (thank you!) are conical with a slight taper at the tip. It really seems to me they stay round when they meet the main body and the other tubercules. In a lot of cases there is space between them, so they don't deform their neighbors at all.

I'm looking for M. glochidiata pictures, and that may be it. At the link below, some (but not all) of this man's pictures look like a hit. The early ones look very similar, but the later ones seem to be one solid mass instead of a pile of puffballs. You can see the tubercule shape for sure though.

I hope it is one, since it appears on "The IUCN List of Threatened Species".
If it turns out to be one of these, how can I help? I'd be glad to share pieces of this one if people want to adopt them. (And if you tell me the correct way to separate them so they will grow for other people...)

I have a friend with a camera with a good macro lens, so I will try to post another picture or two here in the next couple days.

Here is a link that might be useful: scroll down to the glochidiatas

Nearly every cactus is somewhat endangered in the wild, many of them on the red list, more than a few are extinct in the wild. This is primarily due to habitat destruction, but in a few cases is due to collection for sale. M. glochidiata is relatively common in cultivation and not in danger of disappearing. Individual heads can be twisted off and rooted as a cutting if you want to create one or two spare plants.

The radial spines are usually paler and weaker than the centrals, often completely white, and sometimes reduced to fine hairs. They should be flexible but strong on M. glochidiata.

Plants grown in bright light, and not overwatered or heavily fertilised, will form more compact clumps. Watering in low light is especially bad. In low light or with too much water, they will stretch and the individual heads will stick out more. They don't need much water, a large plant like this can go through winter completely dry in a frost-free porch or other cool bright place. Water only when completely dry. Take care to soak the pot thoroughly a couple of times every year to make sure that the central portions of the clump are kept alive.

That last bit should read "In summer, water only when completely dry".

Will do. Thank you.

At long last my friend with the good camera came by to take clearer photos.

Do these help to confirm or deny the M. glochidiata diagnosis? (The longer white threads are probably cat hairs, for what it's worth...didn't get to tidy up before he started snapping photos!)

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