The single white tipped stalk (stigma) is the girl part and the crisp yellow nuggets (anthers) are the boy parts and the soft purple tentacles are footholds for the bees that come to pollinate. In order that the plant not pollinate itself, the parts 'ripen' at different times, so when the pollen is ripe and being carried around, the stigma is not receptive. Thus a flower must be pollinated not by itself by by pollen on the bee from another flower. This is what keeps the genetics mixed up and allows for the diversity that allows for evolution. And all this must happen in the half day that spiderworts are in bloom, for the petals open in the early morning and turn to drippy mush by early afternoon. They are one of those flowers whose petals seem to be made up of a mass of glistening jewels, and they are a treasure all the more valuable because unless you are up and about the prairie well before noon, you will miss them in their glory!