According to observations of naturalists and beekeepers.
Where are you?
NECTAR PRODUCTION:
56 - 112 kilograms per ha
SOURCE FOR HONEY BEES:
Minor
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.
Brassica napus (aka: Rapeseed)
Allium schoenoprasum (aka: Chives)
Sinapis arvensis (aka: Charlock mustard, California rape, Charlock, Corn mustard, Canola, Kaber mustard, Rapeseed mustard)
Calendula officinalis (aka: Marigold, Calendula, Pot marigold, English marigold)
Agastache foeniculum (aka: Giant hyssop, Blue giant hyssop, Anise hyssop, Fragrant giant hyssop, Lavender giant hyssop)
Chamaenerion angustifolium (aka: Fireweed, Great willowherb, Rosebay willowherb, Saint Anthony's Laurel, French-willow)
Cucumis melo (aka: Cantaloupe, Rockmelon, Sweet melon, Spanspek, Honeydew melon, Honeymelon, Crenshaw, Casaba)
Borago officinalis (aka: Borage, Starflower, Common borage, Cool-tankard, Tailwort)
Cirsium arvense (aka: Creeping Thistle, Canada thistle, Field thistle, California thistle, Lettuce from hell thistle, Corn thistle, Cursed thistle, Green thistle, Hard thistle, Perennial thistle, Prickly thistle, Small-flowered thistle, Way thistle, Stinger-needles)
Calluna vulgaris (aka: Heather, Scotch heather, Common heather, Ling, Simply heather)