According to observations of naturalists and beekeepers.
Where are you?
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.
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.