Swamp Black Gum flower (Nyssa sylvatica var. biflora)

2012-5-16 PL, DE
http://www.carolinanature.com/trees/nysy.html
(was Duke)

We're in the northern part of its range as you can see if you scroll down to the map:
http://plants.usda.gov/java/profile?symbol=NYBI&photoID=nybi_001_avd.tif