This is an image of grains of pollen, which appear as small light brown and dark brown dots.

This sample of pollen was obtained on May 8, 2019 at 3pm, from the bush of purple flowers north of the Guggenheim building on Caltech campus. (Pasadena, CA)

This sample was obtained by picking a flower with a visible amount of pollen on its pistil. The pollen was collected in a drop of water on the end of a stick, and mounted on a glass slide.

The flower itself appears to be Serbian bellflower ( Campanula poscharskyana ), and since it is surrounded by other Serbian bellflowers, I guess this pollen is from Serbian bellflower.

#caltechbi1