sterile stamens in some flowers

a sterile stamen, often rudimentary, sometimes modified, e.g. petaloid.

A sterile stamen-like part of the flower, may look like a petal but in typical position of a stamen

In botany, a staminode is an often rudimentary, sterile or abortive stamen. This means that it does not produce pollen. Staminodes are frequently inconspicuous and stamen-like, usually occurring at the inner whorl of the flower, but are also sometimes long enough to protrude from the corolla.