According to observations of naturalists and beekeepers.
Where are you?
SOURCE FOR HONEY BEES:
Common hackberry is most common in the midwestern United States. It is sparingly distributed in Manitoba, Ontario, and Quebec, rare along the Atlantic coast from Massachusetts to Virginia, occasional in Tennessee, North Carolina, and Georgia, and restricted to Hemphill County in the Texas panhandle.
Common hackberry tolerates a range of climatic and soil conditions. Although most common along rivers and streams, it also occurs in open woodlands, rocky hillsides, limestone outcrops, and sand barrens throughout its North American range.
This plant is present in at least 45 states/provinces in this country.
Common hackberry typically grows as a broad tree measuring around 50 feet (15 m) tall and 20 inches (50 cm) in diameter; however, size and growth form can vary with site conditions. Common hackberry trees may reach 110 feet (35 m) tall and 6 feet (1.8 m) in diameter. Common hackberry bark is thick, deeply furrowed, and develops warty cork projections with age.
Common hackberry is symmetrical and open-branched, with larger branches 26 to 33 feet (8-10 m) above ground. The crown is ascending with spreading branches, which droop at the tips. Common hackberry is sensitive to mites (Eriophyes spp.), which cause witches' brooms or thick clusters of branches and twigs. It produces simple leaves, which are arranged alternately, measure 1.2 to 6.7 inches (3-17 cm) long, and are about twice as long as they are wide. Leaves have serrated margins with 10 to 40 teeth per side, at least on the upper half. Leaves are triangular with uneven sides, long tapered tips, and 3 prominent veins from the same basal point. Common hackberry trees produce both male and female flowers. Pistillate and staminate flowers are usually solitary but also occur in clusters of up to 3. Pistillate flowers are borne in the axils of new leaves, and staminate flowers are borne at the ends of new branches. Common hackberry produces solitary, single-seeded drupes that are 8 to 11 mm in diameter.
Common hackberry produces flowers at the same time as leaves, which is typically in April or May. Flowers are typical in early April in the southern part of the common hackberry's range and in late May in the northern part of its range. Fruits are often ripe in September or October but remain on the tree until winter or spring.
Allium schoenoprasum (aka: Chives)
Brassica napus (aka: Rapeseed)
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)
Cucumis sativus (aka: Cucumber, Cetriolo, Gherkin)
Cucumis melo (aka: Cantaloupe, Rockmelon, Sweet melon, Spanspek, Honeydew melon, Honeymelon, Crenshaw, Casaba)
Citrullus lanatus (aka: Watermelon)
Borago officinalis (aka: Borage, Starflower, Common borage, Cool-tankard, Tailwort)
Asteraceae (aka: Aster, Daisy, Composite)