According to observations of naturalists and beekeepers.
Where are you?
30 kilograms per ha
SOURCE FOR HONEY BEES:
Major in some areas
Smooth blackberry's range extends from Newfoundland to Ontario and along the Atlantic Coast south to Georgia and inland to Kentucky and Tennessee.
Smooth blackberry is a common understory species in open deciduous forests, on mountain ridges, and in disturbed areas.
This rhizomatous shrub forms thickets up to 2 to 3 meters (7–10 feet) tall. The leaves are deciduous and alternately arranged, each measuring 10 to 20 centimeters (4-8 inches) long. The inflorescence is a cluster of up to 25 flowers. The fruit is an aggregate of many small drupes, each of which contains a tiny nutlet. The plant reproduces by seed, by sprouting up from the rhizome, and by layering. The stems can grow one meter (40 inches) in height in under two months.
Smooth blackberry grows across a wide range of sites throughout the cool, moist climate of the Northeast. It is very common in woods, old fields, cool hollows, and along roadsides.
Smooth blackberry flowers from May to June. Fruits ripen in early summer and persist into September. The seed disperses in September.