According to observations of naturalists and beekeepers.
Where are you?
800 – 1,100 pounds per acre
SOURCE FOR HONEY BEES:
The native range of American basswood extends from southwestern New Brunswick and Maine west to southern Quebec, southern and western Ontario, Michigan, Minnesota, and southeastern Manitoba; south to eastern North Dakota, northern and eastern Nebraska, eastern Kansas, and northeastern Oklahoma; east to northern Arkansas, Tennessee, western North Carolina, and New Jersey.
This plant is present in at least 43 states/provinces in this country.
The American basswood is a medium-sized to a large deciduous tree reaching a height of 18 to 37 m (60 to 120 ft) exceptionally 39 m (128 ft) with a trunk diameter of 1–1.5 m (3–5 ft) at maturity. It grows faster than many North American hardwoods, often twice the annual growth rate of American beech and many birch species. Life expectancy is around 200 years, with flowering and seeding generally occurring between 15 and 100 years, though occasionally seed production may start as early as 8 years.
The leaves are simple, alternately arranged, ovate to cordate, asymmetrical, unequal at the base (the side nearest the branch the largest), 10–15 cm (4–6 in) (can grow up to 25 cm or 10 in) long and broad, with a long, slender petiole, a coarsely serrated margin and an acuminate apex.
The flowers are small, fragrant, yellowish-white, 10–14 mm (13⁄32–9⁄16 inch) in diameter, arranged in drooping, cymose clusters of 6–20 with a whitish-green leaf-like bract attached for half its length at the base of the cyme.
American basswood usually flowers in June, but flowering dates range from late May to early July. Flowering occurs from 1 to 4 weeks after spring leaf-out. In Minnesota, bud swell occurs from late April to early May, and leafing out occurs from early to mid-May. Seeds are dispersed in October, and leaf fall occurs from September to October.
Sinapis arvensis (aka: Charlock mustard, California rape, Charlock, Corn mustard, Canola, Kaber mustard, Rapeseed mustard)
Asclepias syriaca (aka: Сommon milkweed, Butterfly flower, Silkweed, Silky swallow-wort, Virginia silkweed)
Brassica rapa (aka: Field mustard, Common mustard, Wild mustard, Wild turnip, Forage turnip, Wild rutabaga, Birdsrape mustard, Rape mustard)
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)
Agastache foeniculum (aka: Giant hyssop, Blue giant hyssop, Anise hyssop, Fragrant giant hyssop, Lavender giant hyssop)
Borago officinalis (aka: Borage, Starflower, Common borage, Cool-tankard, Tailwort)