The lovely big plant in this picture is not a Dudleya. It looks like an agave to me, though it could be something else. I'm guessing the Dudleya in the arboretum may be one of the small finger plants above it or to the upper left. The agave could be A. filifera, but that's just a guess. Maybe @mcvansoest can help with the ID, or maybe you have some additional info from the arboretum which would help pin it down. Any ideas?

I agree that it is an Agave, but to get a positive ID on the stringy ones is not always straightforward. filifera sounds good to me, but I am certainly not sure about that.

I'm going by the filaments, the size, and the apparent non-offsetting behavior. It's as good a guess as any, I think.

Bleu, is it okay with you if I propose this image be moved to the corresponding agave page?

Yes, Baja, please move it. And thank you for keeping a watchful eye. I do a lot of research/comparison before uploading an image to the database but when the photo is from a botanical garden or similar institution and has a sign I tend to trust it. I guess I'll be less trusting from now on...

You'd be surprised how many incorrectly labeled plant photos get submitted from botanical gardens!

I talked to the Desert Botanical Garden people in Phoenix about it. They said the plant names change so often they can't keep up.

On top of that, plants are prone to dying and often cannot be replaced right away, or ever. Between the plants dying, the tags moving around for no good reason, and the names changing every few years, the name game never ceases in bot gardens. The idea of making a little metal plate and planting it forever is unfortunately a bit disconnected from reality. As is, I suppose, the trust that we gardeners place in these institutions to get the details right every time.