Can anyone give me some advice or point me towards some literature on identifying the differences between Lophophora williamsi, Lophophora diffusa, Lophophora fricii, and any other species/variations? I can hardly find anything on the subject online, aside from a few sources saying that L. williamsi and L. diffusa are practically indistinguishable to the untrained eye. I can't find anything regarding L. fricii anywhere.
Anyone feel like giving some advice to an amateur cactophile?

I found a few pictures reported to be of L. fricii, but I couldn't distinguish between the different Lophophora species to save my life!

After a while of compulsively collecting and viewing pictures of lophophora online you'll start to be able to tell which species it is immediately.

By the way AKL. That paper on lophophora alberto-vojtechii is great. I recently came across a couple hundred seeds and sowed a bunch. Can't wait to see them get bigger.

Thanks guys! AlbertKLloyd, I really appreciate all the pdf's. I'll definitely be spending the rest of the night reading through them!

So I read through AKL's links, and I'm still not confident in my ability to tell the difference...

What do you folks think of these little guys which I recently came across? My first impression was L. diffusa, but as I continue to read more on the topic I start to wonder if there isn't a chance they are L. williamsii. The solo button looks like he might flower some time in the near future, so that might help me to determine the species. If anyone has an idea, it is more than welcome!

Flowers will help. I believe L. williamsii has light pink flowers, where diffusa has a white flower, and fricci has a deep pink flower.

I would guess you are correct to assume they are both Williamsii. The caespitose loph just looks young. We're they not labeled?

They were gifted, and the previous caretaker was not well versed on the various Lophophora species.

The all look like Petes to me.

I would guess they are L willy.
I however am not an expert.

Pete's?

I should have a verified L. williamsii to add to my little garden within the next week, so it might be easier for me to figure it out when I can compare and contrast.

The only reason I suspected diffusa is because the ribs on the solo-button are just slightly hourglass-shaped, like they mention in that pdf that you linked.

Thanks AKL and ez!

There is a lot of variation in L. williamsii.

Yea, that's what I'm coming to realize. After reading a bit more on the subject I'm fairly confident that they are some variety of williamsii.

I concur with AKL.

AlberKLoyd, do you have any thoughts on whether L. williamsii var decipiens is actually a williamsii or a different species. That variation (or species) has a pretty distinct rib pattern than most of the other williamsii variations. I've heard it called L. fricii var. decipiens, L. williamsii var. decipiens and then Lophophora decipiens. Even the Mesa Gardens website sells seeds in the US labelled Lophophora decipiens seeds for sale. Which, if it is actually a williamsii, would be illegal. Which kind of confused me. Maybe it's just a loophole around it so they can sell williamsii seeds.

Here's a williamsii then a decipiens.

For the of argument let'e consider it a seperate species, however the reasoning behind that might be a bit questionable in the taxonomic sense. I do not have enough information about the ratio of alkaloids it has or the ability it does or does not have to cross with other species in the genus and so cannot do more than speculate.
Having grown it before I found it to be taxonomically confusing.

Whoa, that is a very interesting rib pattern. Has anyone done an analysis on a decipiens or harvested and eaten a couple? It would be pretty exciting if it were determined to be a different species than williamsii, but it contained mescaline in comparable amounts.

I believe this website could help you a lot...
http://www.magicactus.com

Thank you, Dante. I actually discovered that website sometime shortly after making this thread.