According to observations of naturalists and beekeepers.
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Grayleaf willow grows throughout most of Alaska except for the Aleutian Islands and along the southeastern coast. It grows through much of northern Canada from Newfoundland northwest to the northern Yukon Territory, and south to southern British Columbia and Alberta. In the contiguous United States, it grows in alpine and subalpine habitats in Montana, Wyoming, eastern Idaho, Colorado, Utah, and northern New Mexico.
This plant is present in at least 20 states/provinces in this country.
Grayleaf willow commonly grows as an erect shrub 3 to 4 feet (0.9-1.2 m) tall. On exposed tundra sites it grows as a low, semi prostrate shrub, and on favorable sites, it sometimes grows up to 20 feet (6 m) in height and 5 inches (12 cm) in diameter. The bark is gray and smooth but may become rough and furrowed on larger individuals.
Male and female flowers occur on separate plants in 3/4- to 2-inch-long (2-5 cm) catkins that persist over the summer.
The fruit is a 1/32- to 1/16-inch-long (0.8-1.6 mm) two-valved capsule.
Grayleaf willow catkins appear with the leaves. In Alaska and the Yukon, flowering generally occurs in June, the fruits ripen in July and August and the seeds are dispersed in late August and September.
Cercis canadensis (aka: Eastern redbud, Redbud, Cersis Reniformis)
Celtis laevigata (aka: Hackberry, Sugarberry, Lowland hackberry, Sugar hackberry, Arizona sugarberry, Netleaf hackberry, Small's hackberry, Southern hackberry, Texas sugarberry)
Pyrus communis (aka: European pear, Common pear)
Acer negundo (aka: Boxelder, Western boxelder, Arizona boxelder, California boxelder, Texas boxelder, Interior boxelder, Violet boxelder)
Ungnadia speciosa (aka: Mexican buckeye, Texas buckeye, Canyon buckeye, Spanish buckeye, New Mexican buckeye, New Mexico buckeye, False buckeye, Monillo, Monilla)
Acer glabrum (aka: Rocky Mountain maple, Douglas maple, Greene's maple, New Mexico maple, Torrey maple)
Salix lucida (aka: Shining willow, Greenleaf willow, Tail-leaf willow, Whiplash willow, Pacific willow, Lance-leaf willow, Longleaf willow, Red willow, Western shining willow)
Malus domestica (aka: Pyrus pumila, Malus pumila, Apple)
Prunus cerasus (aka: Sour cherry, Tart cherry, Dwarf cherry, Montmorency cherry)
Prunus americana (aka: American plum, Goose plum, River plum, Wild plum)
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)
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)
Salix amygdaloides (aka: Peachleaf willow, Peach leaf willow)
Salix drummondiana (aka: Drummond's willow, Beautiful willow, Blue willow)
Salix boothii (aka: Booth's willow)
Robinia pseudoacacia (aka: Black locust, False acacia, Yellow locust, White locust, Green locust, Post locust, Falsa acacia, Robinia)
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 monticola (aka: Park willow, Cherry willow, Mountain willow, Serviceberry willow, White willow)
Rhus glabra (aka: Smooth sumac, Common sumac, Rocky Mountain sumac, Red sumac, Western sumac, White sumac)
Brassica napus (aka: Rapeseed)
Sinapis arvensis (aka: Charlock mustard, California rape, Charlock, Corn mustard, Canola, Kaber mustard, Rapeseed mustard)
Gleditsia triacanthos (aka: Honey locust, Honey shucks locust, Common honeylocust, Sweet bean locust)
Asclepias tuberosa (aka: Butterflyweed, Butterfly Milkweed, Orange Milkweed, Pleurisy Root, Chigger Flower, Canada root, Fluxroot, Indian paintbrush, Indian posy, Orange root, Orange Swallow-wort, Tuber root, Yellow milkweed, White-root, Windroot, Butterfly love)
Prunus virginiana (aka: Chokecherry, Western chokecherry, Common chokecherry, Black chokecherry)