White Poplar: Populus alba (Synonyms: Populus alba var. bolleana, Populus alba var. pyramidalis) - Non-native, naturalized.
Necklace Poplar: Populus deltoides ssp. monilifera (Synonym: Populus deltoides var. occidentalis) - Non-native, naturalized.
Fremont Cottonwood: Populus fremontii ssp. fremontii - Non-native, not naturalized.
Black Cottonwood, Lombardy Poplar: Populus nigra (Synonyms: Populus dilatata, Populus italica, Populus nigra var. italica) - Non-native, naturalized.
Quaking Aspen: Populus tremuloides (Synonym: Populus tremula ssp. tremuloides) - Native.
Black Cottonwood: Populus trichocarpa (Synonyms: Populus balsamifera, Populus balsamifera ssp. trichocarpa, Populus balsamifera var. californica, Populus trichocarpa var. cupulata, Populus trichocarpa var. ingrata) - Native.
Gray Poplar: Populus xcanescens - Non-native.