According to observations of naturalists and beekeepers.
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Field mustard is an upright winter annual or biennial that is a member of the mustard family (Brassicaceae). The oil made from the seed is sometimes also called canola or colza, which is one reason why it is sometimes confused with rapeseed oil.
This species is native to Eurasia, but has spread all over the world and is now naturalized throughout much of North America.
This plant is present in at least 63 states/provinces in this country.
Plants exist as basal rosettes until flowering stems develop at maturity, usually in the second year. Plants grow 1 to 3 (or 4) ft tall from a sometimes fleshy, enlarged taproot, with a many-branched stem. The foliage is generally hairless and sometimes covered with a whitish film. Lower leaves can reach 12 inches long, have a large central lobe, and usually one to four pairs of smaller side lobes. Upper leaves are smaller, non-lobed, and have a pointed tip and widened, clasping base. The bright yellow flowers are clustered at stem tops and have four petals that are 1/4 to 1/2 inch long.
Plants flower from June to August, depending on climate and latitude, and are insect-pollinated and self-incompatible.
Acer saccharinum (aka: Silver maple, Soft maple)
Cercis canadensis (aka: Eastern redbud, Redbud, Cersis Reniformis)
Malus angustifolia (aka: American crab apple, Buncombe crab apple, Crabtree, Narrowleaf crab, Narrowleaf crab apple, Southern crab, Southern crab apple)
Aronia arbutifolia (aka: Red chokeberry)
Prunus americana (aka: American plum, Goose plum, River plum, Wild plum)
Prunus serotina (aka: Black cherry, Wild black cherry, Rum cherry, Mountain black cherry, Wild cherry)
Vaccinium corymbosum (aka: Highbush blueberry, High-bush blueberry, Northern highbush blueberry, Tall blueberry, Rabbiteye blueberry, Blue huckleberry, Tall huckleberry, Swamp huckleberry, High blueberry, Swamp blueberry)
Celtis laevigata (aka: Hackberry, Sugarberry, Lowland hackberry, Sugar hackberry, Arizona sugarberry, Netleaf hackberry, Small's hackberry, Southern hackberry, Texas sugarberry)
Pyrus communis (aka: European pear, Common pear)
Acer negundo (aka: Boxelder, Western boxelder, Arizona boxelder, California boxelder, Texas boxelder, Interior boxelder, Violet boxelder)
Celtis occidentalis (aka: Common hackberry, Bastard elm, Nettle-tree, Northern hackberry)
Ilex opaca (aka: American holly, Dune holly, Hummock holly, Scrub holly)
Malus domestica (aka: Pyrus pumila, Malus pumila, Apple)
Malus coronaria (aka: Sweet crab apple, Garland crab, Alabama crab, Allegheny crab, American crab, Baltimore crab apple, Buncombe crab, Dawson crab, Dunbar crab, Fragrant crab, Garland tree, Lanceleaf crab apple, Missouri crab, Sweet-scented crab, Sweet wild crab, Wild crab, Wild sweet crab, Wild Crab Apple)
Acer saccharum (aka: Sugar maple, Rock maple, Hard maple)
Liriodendron tulipifera (aka: Tuliptree, Blue-poplar, Tulip-poplar, Yellow-poplar, Yellow wood)