Stamen of vegetable marrow with pollen grains. These grains are slightly smaller than pollen of common hollyhock, and have similar shape (sphere with small spikes), but on these grains we can see also bigger spikes. For comparison, here you'll find an electronic microscopy image of marrow pollen grain:
sciencephoto.com/media/33205/view
Gear: my usual "snowflake" macro setup (i described it in article about snowflake macro photography). Daylight from left side, no diffusor, no reflector. Averaged stack of 64 identical shots.
Here is my first photo in this series: very big pollen grains of Alcea Rosea, separated on black glass:
