According to observations of naturalists and beekeepers.
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15 kilograms per ha
SOURCE FOR HONEY BEES:
Viburnum prunifolium, commonly called black haw, is usually grown as a large, upright, multi-stemmed, deciduous shrub with an irregular crown, but it also may be grown as a small, single trunk tree.
Genus name comes from the Latin name of a species plant.
Specific epithet means with leaves like Prunus.
Common name refers to the purported similarity of this plant to hawthorns (sometimes commonly called red haws), though hawthorns are in a different family.
This plant is present in at least 27 states/provinces in this country.
It is a deciduous shrub or small tree growing to 2–9 meters (7–30 ft) tall with a short crooked trunk and stout spreading branches; in the northern parts of its range, it is a shrub, becoming a small tree in the southern parts of its range. The bark is reddish-brown, very rough on old stems. The branchlets are red at first, then green, finally dark brown tinged with red. The winter buds are coated with rusty tomentum. The flower buds ovate, 1 cm long, much larger than the axillary buds. The leaves are simple, up to 9 cm long and 6 cm broad, oval, ovate or orbicular, wedge-shaped or rounded at base, serrate, acute, with serrated edges with a grooved and slightly winged red petiole 1.5 cm long; they turn red in fall. The leaves are superficially similar to some species of Prunus; they come out of the bud involute, shining, green, tinged with red, sometimes smooth, or clothed with rusty tomentum; when full grown dark green and smooth above, pale, smooth or tomentose beneath.
Viburnum prunifolium flowering from May to June, depending on location.
Brassica napus (aka: Rapeseed)
Allium schoenoprasum (aka: Chives)
Sinapis arvensis (aka: Charlock mustard, California rape, Charlock, Corn mustard, Canola, Kaber mustard, Rapeseed mustard)
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)
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)
Chamaenerion angustifolium (aka: Fireweed, Great willowherb, Rosebay willowherb, Saint Anthony's Laurel, French-willow)
Citrullus lanatus (aka: Watermelon)