According to observations of naturalists and beekeepers.
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Asclepias syriaca, commonly called common milkweed, butterfly flower, silkweed, silky swallow-wort, and Virginia silkweed, is a species of flowering plant. It is in the genus Asclepias, the milkweeds. This species is native to southern Canada and of much of the conterminous eastern U.S., east of the Rocky Mountains, excluding the drier parts of the prairies. It grows in sandy soils and other kinds of soils in sunny areas.
This plant is present in at least 46 states/provinces in this country.
Common milkweed is a clonal perennial herb growing up to 2.6 m tall. Its ramets grow from rhizomes. All parts of common milkweed plants produce white latex when broken. The simple leaves are opposite or sometimes whorled; broad ovate-lanceolate; up to 25 cm long and 12 cm broad, usually with entire, undulate margins and reddish main veins. They have very short petioles and velvety undersides.
The highly fragrant, nectariferous flowers vary from white (rarely) through pinkish and purplish and occur in umbellate cymes. Individual flowers are about 1 cm (0.4 in) in diameter, each with five cornate hoods and five pollinia. The seeds, each with long, white flossy hairs, occur in large follicles. Fruit production from selfing is rare. In three study plots, outcrossed flowers had an average of about 11% fruit set.
Bloom Time: June to August.
Acer rubrum (aka: Red maple, Scarlet maple)
Acer negundo (aka: Boxelder, Western boxelder, Arizona boxelder, California boxelder, Texas boxelder, Interior boxelder, Violet boxelder)
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)
Aesculus californica (aka: California buckeye, Buckeye, Horsechestnut)
Rubus spectabilis (aka: Salmonberry)
Acer glabrum (aka: Rocky Mountain maple, Douglas maple, Greene's maple, New Mexico maple, Torrey maple)
Salix lucida (aka: Shining willow, Greenleaf willow, Tail-leaf willow, Whiplash willow, Pacific willow, Lance-leaf willow, Longleaf willow, Red willow, Western shining willow)
Salix exigua (aka: Narrowleaf willow, Coyote willow)
Acer macrophyllum (aka: Bigleaf maple, Big-leaf maple, Oregon maple)
Crataegus douglasii (aka: Black hawthorn, Douglas hawthorn, River hawthorn, Western thornapple)
Populus tremuloides (aka: Quaking aspen, Trembling aspen, Aspen, American aspen, Mountain aspen, Golden aspen, Trembling poplar, White poplar, Popple, Alamo Blanco)
Acer circinatum (aka: Vine maple)
Prunus emarginata (aka: Bitter cherry)
Prunus pumila (aka: Sandcherry, Western sandcherry, Eastern sandcherry, Great Lakes sandcherry)
Salix scouleriana (aka: Scouler's willow, Upland willow)
Malus fusca (aka: Oregon crab, Oregon crab apple, Pacific crab apple, Western crab apple)
Salix bebbiana (aka: Bebb willow, Beak willow, Beaked willow, Long-beaked willow, Diamond willow, Chaton, Petit Minou, Smooth Bebb willow)
Malus domestica (aka: Pyrus pumila, Malus pumila, Apple)
Acer platanoides (aka: Norway maple)
Rubus ursinus (aka: California blackberry, California dewberry, California grapeleaf dewberry, Douglasberry, Pacific blackberry)
Salix drummondiana (aka: Drummond's willow, Beautiful willow, Blue willow)
Salix lemmonii (aka: Lemmon's willow, Lemmon willow)
Salix boothii (aka: Booth's willow)
Salix lutea (aka: Yellow willow)
Salix planifolia (aka: Diamondleaf willow, Planeleaf willow)
Salix amygdaloides (aka: Peachleaf willow, Peach leaf willow)
Robinia pseudoacacia (aka: Black locust, False acacia, Yellow locust, White locust, Green locust, Post locust, Falsa acacia, Robinia)
Ajuga reptans (aka: Bugle, Blue bugle, Bugleherb, Bugleweed, Carpetweed, Carpet bugleweed, Common bugle, St. Lawrence plant)
Astragalus (aka: Milkvetch, Locoweed, Goat's-thorn)
Rubus laciniatus (aka: Cutleaf blackberry, Evergreen blackberry, Slashed blackberry)
Rhus glabra (aka: Smooth sumac, Common sumac, Rocky Mountain sumac, Red sumac, Western sumac, White sumac)
Salix geyeriana (aka: Geyer willow, Silver willow)
Brassica napus (aka: Rapeseed)
Allium schoenoprasum (aka: Chives)
Sinapis arvensis (aka: Charlock mustard, California rape, Charlock, Corn mustard, Canola, Kaber mustard, Rapeseed mustard)
Prunus virginiana (aka: Chokecherry, Western chokecherry, Common chokecherry, Black chokecherry)
