In the upper left is a longitudinal section of a flower of a prairie plant, Anemone cylindrica, thimbleweed (Ranunculaceae). The receptacle is elongate (lower arrow) and surrounded by many distinct carpels. After the petals and stamens fall off, the receptacle becomes hard, and each carpel matures into an achene.
The achenes are covered with many fine hairs that aid in dispersal by wind.
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