According to observations of naturalists and beekeepers.
Where are you?
Yellow willow is found at low to mid-elevations from Alberta to Manitoba, south to western Kansas and New Mexico, west to Arizona and California, and north along the Sierra Nevada Mountains to eastern Washington. It is lacking in the Great Basin.
This plant is present in at least 21 states/provinces in this country.
Yellow willow is a deciduous shrub, or rarely, a small tree up to 23 feet (7 m) tall, with stems diameters up to 8 inches (20 cm). The silvery-gray bark of older twigs distinguishes it from many closely related willows. The leaves are alternate, simple, pinnately veined, mostly lanceolate, with finely serrate margins, dark green to yellow-green above and pale or glaucus beneath, with conspicuous stipules usually present. Male and female flowers occur on separate plants as catkins. Staminate catkins are .8-2 inches (2-5 cm) long, and pistillate catkins are .8-2.7 inches (2-7 cm) long, but mostly under 1.5 inches (4 cm).
Yellow willow is a deciduous shrub or rarely small tree. Its catkins emerge before and with the leaves in the spring. After fruits ripen, seeds are dispersed from spring to early summer.
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)
Prunus pumila (aka: Sandcherry, Western sandcherry, Eastern sandcherry, Great Lakes sandcherry)
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)
Malus domestica (aka: Pyrus pumila, Malus pumila, Apple)
Prunus americana (aka: American plum, Goose plum, River plum, Wild plum)
Salix amygdaloides (aka: Peachleaf willow, Peach leaf willow)
Celtis occidentalis (aka: Common hackberry, Bastard elm, Nettle-tree, Northern hackberry)
Vaccinium angustifolium (aka: Lowbush blueberry, Early low-bush blueberry, Low sweet blueberry)
Acer spicatum (aka: Mountain maple, Low maple, Moose maple, Water maple, Plaine batarde, Fouereux)
Salix nigra (aka: Black willow, Swamp willow, Southwestern black willow, Gulf black willow, Scythe-leaved willow)
Salix planifolia (aka: Diamondleaf willow, Planeleaf willow)
Astragalus (aka: Milkvetch, Locoweed, Goat's-thorn)
Rubus idaeus (aka: Raspberry, Black-haired red raspberry, Brilliant red raspberry, American red raspberry, Red raspberry, Smoothleaf red raspberry, Wild raspberry, Wild red raspberry, Grayleaf raspberry)
Salix alaxensis (aka: Feltleaf willow, Alaska willow)
Salix lutea (aka: Yellow willow)
Salix richardsonii (aka: Richardson's willow, Woolly willow)
Rhus glabra (aka: Smooth sumac, Common sumac, Rocky Mountain sumac, Red sumac, Western sumac, White sumac)
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)
Prunus virginiana (aka: Chokecherry, Western chokecherry, Common chokecherry, Black chokecherry)
Rhamnus cathartica (aka: Common buckthorn, European buckthorn, Dahurian buckthorn)