I went to the Arizona Garden at Stanford University not long ago.  I'd been there a few times before--it's a wonderful place to check out all kinds of agaves, cacti, and crassulae especially.  Soon, I'll post a few more pictures of my most recent visit.  But first, I was wondering if anyone can help me identify these two agaves.  I didn't notice them on my last visit (perhaps I was less agave-aware then?), and they both caught my eye immediately.

This one stood about two feet tall and almost as wide.  The leaves were covered with a white powder that didn't brush off very much when I touched it:

This second one is also gorgeous.  It actually looks a little like my agave blue glow, both in the blue-green color of the leaves and in the outlining of the leaves--except that instead of being outlined in red like a blue glow would be, the leaves of this one were outlined in white. 

Can any agave aficionados out there help me out?  I'd love to know what these are!