The close-up at the left shows two flowers. Notice that each Kudzu flower has the typical papilionaceous configuration described on our Bean-flower Page, plus each flower bears a yellow spot at the base of its large upper petal, the standard. This yellow spot helps pollinators find nectar, and thus facilitates pollination.
As the picture above shows, one feature distinguishing Kudzu flowers from the blossoms of "average" Bean Family members is that the flower's keel -- the two bottom petals grown together to form a scoop-like pouch -- is strongly up-curved at the end, and holds the pistil and stamens inside it very tightly. Compared to the broadly flaring standard, the keel is narrow and smallish.
The picture at the right shows another distinguishing feature: The Kudzu flower's sepals are especially long. In the picture you can see three rather long, narrow, pale-purple sepals arising at the corolla's base, which is at the picture's top, left corner. The pale, small teardrop thing at the calyx's base is a bract (a much-reduced leaf) and thus not really part of the flower.
In the photo at the left I've removed one wing and one side of the keel to show how the filaments of the flower's ten stamens grow together to form a cylinder around the female pistil, but one stamen grows apart. This is typical in the Bean Family. When stamen filaments grow in this manner they are said to be diadelphous. I don't know why so many Bean Family flowers do this strange thing, they just do... Of course, the yellow, powdery stuff at the top left in the picture is pollen being released from mature anthers.