Tetratheca ciliata is known commonly as Black-eyed Susan or as Pink Bells . Each flower has four dark purple stames but pollen is not usually found on the outside of these. The anthers have a circular hole at the top and may well operate by buzz-pollination. To operate such flowers, the insect has to produce a sound of a certain frequency and this dislodges the pollen. Bees are likely candidates for such pollination mechanisms but no major pollinator for Pink Bells has been identified.

Pollen images
light microscopy
electron microscopy