There are some lovely old Iris in those photos. Of the ones I know,
'Helen McGregor' might be correct but looks pretty iffy to me - wrong color, and
'Taj Mahal' and 'Indian Chief' appear to be correct. I agree with Neil on
the one that he thought looks like 'Tiffany', though it might be something else
similar too (I haven't done a detailed comparison on it yet). The one
labeled 'Blue Shimmer' doesn't look quite right to me, but it might be
correct. It's out of focus on my monitor. As I recall, the real
'Blue Shimmer' is more contrasting, with richer coloring toward the edges and
cleaner white inside of the marginal coloring. The one labeled as
"unmarked" is pretty and very distinctive; it should be easy to identify.
Of the others listed, I'm not closely familiar with 'Allegiance', 'Pink
Fringe', or 'Miss Ilini', but all the rest look wrong.
Even with the problems with naming, they are beautiful photos, and perhaps
some of them are figure-out-able. The one labeled as 'President
Pilkington' is really 'Prairie Sunset'.
A thought comes to mind - just a suggestion. In many gardens (don't
know about Clark - never been there) the Iris are laid out in rows with the
labels at the ends of each variety. I wonder, could the labels have been
switched backwards, following instead of preceding the one they represent?
Then they would be facing the next variety in line instead. In my
experience most gardens have a much better percentage of correct labeling than