Wildflowers: Large-petaled Onion, Utah?

Is this a Large-petaled Onion or a Textile Onion? Is it possible to tell?

Photo taken in Capitol Reef NP, Utah, in late May.

 

It's either Allium macropetalum or Allium textile. This page lists all three that occur in Capitol Reef:
http://www.swcoloradowildflowers.com/White Enlarged Photo Pages/allium.htm

They also indicate how to distinguish between these two by the bract venation, which is not seen from the photograph.

 

Thank you, I guess it is impossible to tell from a picture (I have scrutinized that page).