About five years ago I traveled to Tulsa and stayed with my cousin for the weekend. The garden surrounding her home is her creation and it is beautiful in a relaxed, welcoming way that only hints at her talents as a gardener. When we got to her home there was a large clump of 'Caesar's Brother' Siberian Iris in full bloom. I couldn't look at them, and photograph them, enough while there. My cousin must have noticed because not too long after she gave me a nice sized clump of them. She told me they were slow to establish... but to be patient. She was right... but they did settle in and last year they put on a beautiful show. Thanks, Janie!!!
"Each flower features upright standards and flaring to drooping falls. In comparison to bearded varieties, Siberian irises have smaller beardless flowers, narrower grass-like leaves and an absence of thick fleshy rhizomes. After bloom, the foliage clump will retain its blue-green color into the fall, often displaying showy leaves reminiscent of some ornamental grasses." Siberian Iris grow in a wide variety of soils... but does NOT appreciate too much wet or too much dry... or too much shade.
I became interested in Ural False Spirea when I saw a photo of a magnificent specimen in Michael Dirr's Hardy Trees & Shrubs. Two years ago a very good local nursery had a row of 7 three gallon plants they had not ordered and could not identify. When I told them what they had they tagged them, displayed them and gave me one. These are beautiful shrubs... first to leaf out in spring... new leavers have a pleated look and a champagne-bronze coloration. The bloom clusters are snow white and look somewhat like giant Astilbe. Plant it in full sun and reasonable soil.
Either plant is a superb choice for your garden... while remembering the latter of the two needs room to spread.