The yellow color is very unusual. Variations in the number of petals are more common, as shown below.
Middle Run Valley Natural Area May 2012
Four petals and four stamens.
Middle Run Valley Natural Area April 2009
A normal flower with five petals and five stamens. The style would be three-lobed when mature.
White Clay Creek State Park -- Creek Road April 2012
Six petals and six stamens. Only one stamen appears to be fully developed.
White Clay Creek State Park -- Thompson Station Road April 2012
Seven petals, at first glance, but perhap actually five, two of which are two-lobed. Only three stamens. This shows the fully developed three-lobed style.
White Clay Creek State Park -- Creek Road April 2012
Eight petals and eight stamens.
White Clay Creek State Park -- Possum Hill April 2010
Looks like a lot of petals, but the one at lower left on the middle flower is clearly three-lobed. I think there are actually just five petals.
White Clay Creek State Park -- Creek Road May 2015
Looks like two flowers grown together, with two pistils, nine stamens, nine petals...
White Clay Creek State Park -- Creek Road May 2015
...and three sepals. (Two is normal.)
Woodlawn Tract April 2016
A normal flower with two sepals.
White Clay Creek State Park -- Creek Road May 2018
Delaware Wildflowers
