RESULTS
In total, we used 192 pollen samples, 40 of which were samples of known pollen contents composed of the pollen from field-collectedClarkia anthers, and 152 of which were pollen balls of unknown composition harvested from bees in 2014. Sequencing resulted in 45,847,334 reads, 94% of which aligned to one of the fourClarkia species reference sequences. All reads in known samples post-amplification were consistent with the known composition ofClarkia in the sample (Figure S1), barring one sample with a small number of reads. We attempted to analyze the contents of all 152 pollen balls, but two contained pollen in such low amounts they were excluded.