The small sempervivum interest me, so I have been gradually trying to collect the smaller ones. A couple of sites list sizes like Lynn does here and the Hookeri is rated as a "mini". They can be grown larger than I show in the picture, but that seems to be the size that they grow for me, outdoors and no fertilization.
I have this from a trade (since lost), from a group purchase and from private purchase, but there is a difference in the names I got for all three and some differences in appearance as well. So I am not sure the ID of the plants, whether this is the variety "Hookeri" or a hybrid with the variety "Hookeri".
So Lynn, please forgive me, but I don't want to get into the database stuff at this time. I just want to kick back, relax and enjoy some nice plants. [Subject to change at any time, of course]
Thanks all for the kind comments, here's another pic of a small one, may have posted it before. Sempervivum x barbulatum f/Valle Quarozzo. Note that it's in its messy phase, putting out lots of offsets. It settles down and become a nice clump most of the time. The largest rosette in the pic is 1-1.25", so this one is bigger than the previous. I'm always on the lookout for other tiny ones. Squaw Mountain has a couple of mini species semps listed, but my plant budget is busted badly this year.
(A note on nomenclature: I read the above name as "A Sempervivum hybrid of species 'Sempervivum barbulatum' that is from location Valle Quarozzo")