According to observations of naturalists and beekeepers.
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56 - 112 kilograms per ha
SOURCE FOR HONEY BEES:
The most widespread occurrence of black hawthorn is in the Pacific Northwest, from southeastern Alaska south through British Columbia, Alberta, Washington, and Oregon to northern California. Inland distribution encompasses northern Nevada, Utah, Colorado, and Wyoming, western Montana, and Idaho. Douglas hawthorn may also be found as a disjunct in northern Michigan, Minnesota, Saskatchewan, and southern Ontario.
This plant is present in at least 18 states/provinces in this country.
Black hawthorn is a large shrub or small tree ranging from 3.5 to 13.0 feet (1-4 m) tall and possessing straight, strong thorns 0.5 to 1.0 inch (1.00-2.50 cm) long. Leaves are generally 1.5 to 2.5 inches (3-6 cm) long, broad, and serrated at the tip. Blackish, smooth fruits are about 0.5 inches (1 cm) long. Numerous mosses and lichens are present upon the entire bark system.
Black hawthorn stems are usually clustered from the base or from a point just above the soil surface. Shade-killed lower limbs persist on the stem, creating large, dense thickets. Stems are very flexible and have been shown to withstand avalanche impact pressures of up to 10 tons per square meter.
This plant is flowering from April to May.
Black hawthorn fruits are considered ripe when they are black and lustrous. In Oregon fruit was dispersed from August 16 to 31, and in Washington from July 15 to 30.
Acer saccharinum (aka: Silver maple, Soft maple)
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)
Crataegus douglasii (aka: Black hawthorn, Douglas hawthorn, River hawthorn, Western thornapple)
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 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)
Prunus americana (aka: American plum, Goose plum, River plum, Wild plum)
Salix amygdaloides (aka: Peachleaf willow, Peach leaf willow)
Salix drummondiana (aka: Drummond's willow, Beautiful willow, Blue willow)
Salix planifolia (aka: Diamondleaf willow, Planeleaf willow)
Acer spicatum (aka: Mountain maple, Low maple, Moose maple, Water maple, Plaine batarde, Fouereux)
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)
Rhus glabra (aka: Smooth sumac, Common sumac, Rocky Mountain sumac, Red sumac, Western sumac, White sumac)
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)
Prunus virginiana (aka: Chokecherry, Western chokecherry, Common chokecherry, Black chokecherry)
Rhamnus cathartica (aka: Common buckthorn, European buckthorn, Dahurian buckthorn)