Species Group,Mean pollen grains with tubes,Standard deviation of pollen grains with tubes,Sample size Bombus,31.63,36.36,98 Colletes,22.80,27.19,31 Habropoda,34.49,35.64,39 Large Andrena,13.13,18.44,24 Medium Andrena,23.76,34.34,68 Small Bees,17.63,31.93,8 Xylocopa,13.05,35.81,38