According to observations of naturalists and beekeepers.
Where are you?
This plant is present in at least 13 states/provinces in this country.
Cercis orbiculata (aka: California redbud, Western redbud, Arizona redbud, Judas tree, Cercis occidentalis)
Prunus serotina (aka: Black cherry, Wild black cherry, Rum cherry, Mountain black cherry, Wild cherry)
Salix gooddingii (aka: Goodding's willow, Dudley willow, Valley willow, Western black willow)
Celtis laevigata (aka: Hackberry, Sugarberry, Lowland hackberry, Sugar hackberry, Arizona sugarberry, Netleaf hackberry, Small's hackberry, Southern hackberry, Texas sugarberry)
Acer negundo (aka: Boxelder, Western boxelder, Arizona boxelder, California boxelder, Texas boxelder, Interior boxelder, Violet boxelder)
Acer glabrum (aka: Rocky Mountain maple, Douglas maple, Greene's maple, New Mexico maple, Torrey maple)
Prunus americana (aka: American plum, Goose plum, River plum, Wild plum)
Salix lucida (aka: Shining willow, Greenleaf willow, Tail-leaf willow, Whiplash willow, Pacific willow, Lance-leaf willow, Longleaf willow, Red willow, Western shining willow)
Acer grandidentatum (aka: Bigtooth maple, Canyon maple, Western sugar maple)
Salix exigua (aka: Narrowleaf willow, Coyote willow)
Populus tremuloides (aka: Quaking aspen, Trembling aspen, Aspen, American aspen, Mountain aspen, Golden aspen, Trembling poplar, White poplar, Popple, Alamo Blanco)
Salix scouleriana (aka: Scouler's willow, Upland willow)
Salix lutea (aka: Yellow willow)
Prunus emarginata (aka: Bitter cherry)
Salix bebbiana (aka: Bebb willow, Beak willow, Beaked willow, Long-beaked willow, Diamond willow, Chaton, Petit Minou, Smooth Bebb willow)