Kentucky Lady's Slipper (Cypripedium kentuckiense)

2015-5-16 Mt. Cuba Center, New Castle County, Hockessin, DE
All sources I've found describe it as pale yellow to white lips. This one looks lemon yellow.
If I remember I'll check with the photographer about the color.
-brown/maroon sepals down over the flower
http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242101549
http://www.fs.fed.us/wildflowers/beauty/cypripedium/cypripedium_kentuckiense.shtml
http://www.centerforplantconservation.org/collection/CPC_ViewProfile.asp?CPCNum=1235