According to observations of naturalists and beekeepers.
Where are you?
Littletree willow occurs in central Alaska, the Yukon Territory, and adjacent Northwest Territories eastward throughout the boreal forest to Hudson Bay. It extends southward in the eastern Rocky Mountains to northeastern British Columbia, northern Alberta, Saskatchewan, and Manitoba. Littletree willow does not occur in the contiguous United States.
This plant is present in at least 10 states/provinces in this country.
Acer negundo (aka: Boxelder, Western boxelder, Arizona boxelder, California boxelder, Texas boxelder, Interior boxelder, Violet boxelder)
Salix lucida (aka: Shining willow, Greenleaf willow, Tail-leaf willow, Whiplash willow, Pacific willow, Lance-leaf willow, Longleaf willow, Red willow, Western shining 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 arbusculoides (aka: Littletree willow)
Salix bebbiana (aka: Bebb willow, Beak willow, Beaked willow, Long-beaked willow, Diamond willow, Chaton, Petit Minou, Smooth Bebb willow)
Salix discolor (aka: Pussy willow, American pussy willow, Glaucous willow, Large pussy willow)
Salix drummondiana (aka: Drummond's willow, Beautiful willow, Blue willow)
Salix planifolia (aka: Diamondleaf willow, Planeleaf willow)
Salix pulchra (aka: Tealeaf willow, Flatleaf willow, Flat-leaved willow, Paneleaf willow, Thin red willow)
Salix hastata (aka: Halberd willow)
Astragalus (aka: Milkvetch, Locoweed, Goat's-thorn)
Salix alaxensis (aka: Feltleaf willow, Alaska willow)
Salix richardsonii (aka: Richardson's willow, Woolly willow)
Salix lutea (aka: Yellow willow)
Allium schoenoprasum (aka: Chives)
Brassica napus (aka: Rapeseed)
Sinapis arvensis (aka: Charlock mustard, California rape, Charlock, Corn mustard, Canola, Kaber mustard, Rapeseed mustard)
Prunus pensylvanica (aka: Pin cherry, Fire cherry, Bird cherry)