Here are the data on the three pollen types and the protocol for measuring.
I used the same plant/pollen from each plant and measured at least 30 different pollen grains from each. I didn't use any pollen if its pole faced forward - only if it was sideways.
Bad news - the Ech. ang. and Heli. heli. are very close. Good news - maybe the pollinators and plants can't tell them apart either.
PS - I am in SE Minn and the Monarda Sunflower and Miss. Goldenrod are in full bloom all over.