Anyone know this one? Not on there plant list. Fascinating collection of plants.

That looks like something in the A. gypsophylla complex - I think that species has recently been subdivided into a bunch of new species...

Looks like a Puya.

I was thinking Agave gypsophila or related too.

I'd contact the gardens with a pic and see what they say.

Here are similar looking plants at the same location identified as gypsophila.

https://www.smgrowers.com/info...
https://pieceofeden.blogspot.m...

And on this page it is identified as pablocarrilloi which is a new(ish) name, see reference below.

https://www.succulentsandmore....
https://www.researchgate.net/p...

That last link looks like the same plant. I just wasn't seeing Agave in the OP's photos. Sure is a Puya looking Agave.

Yes, it is definitely the same plant.

I will be moving to add those 2013 agave species to the database shortly, since they appear to be legitimate...

Thanks all. A. gypsophylla/complex. Great links. Ruth didn't like plant tags though many plants had the small metal tabs they were inaccessible in most cases. Many are not current names. Docents there vary in knowledge of the plants growing there. The web sights list of plants is incomplete. Most are volunteers. NGA has always proven to be the most knowlegable resource all in one place. It's a wonderfull "home" garden. Thanks again.

I did contact the curator Brian Kemble and he confirmed that it is (now) A. pablocarrilloi.

Here it is.

Agave (Agave pablocarrilloi)