Stuck with this one. Four sepals, did not dig inside for petals etc., assuming this is a species of Brassicaceae. But now, I noticed that the ovary is inferior. Dug through the Intermountain Flora and could not find any match. Any ideas?
Leaf structure looks very similar to Agrimonia, except Agrimonia flowers have five sepals and petals I believe.
Thanks, Pathe! Derrick Zobell, who is currently working on the Zion Park web site design, preliminary identified it as Camissonia multijuga. I hope to catch it flowering next year, to confirm this ID.