“…Thus, plants commonly receive pollen loads that contain both heterospecific and conspecific pollen (Ashman and Arceo‐Gómez, 2013; Arceo‐Gómez et al, 2015 in this issue). The receipt of mixed‐species pollen loads may have negative effects on recipient reproduction, as heterospecific pollen can interfere with adhesion, hydration, germination, and tube growth of conspecific pollen, as well as reduce ovule and seed development (Sukhada and Jayachandra, 1980; Thomson et al, 1982; Galen and Gregory, 1989; Arceo‐Gómez and Ashman, 2011, 2014a). For instance, a recent synthesis found that all species received heterospecific pollen in at least some of their flowers (range 2–100% of flowers), and hand pollinations with a standard mixed load of heterospecifc and conspecific pollen led to a significant (mean 20%) decrease in seed production (Ashman and Arceo‐Gómez, 2013).…”