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.
Salix lucida (aka: Shining willow, Greenleaf willow, Tail-leaf willow, Whiplash willow, Pacific willow, Lance-leaf willow, Longleaf willow, Red willow, Western shining willow)
Prunus emarginata (aka: Bitter cherry)
Prunus pumila (aka: Sandcherry, Western sandcherry, Eastern sandcherry, Great Lakes sandcherry)
Salix bebbiana (aka: Bebb willow, Beak willow, Beaked willow, Long-beaked willow, Diamond willow, Chaton, Petit Minou, Smooth Bebb willow)
Salix scouleriana (aka: Scouler's willow, Upland willow)
Acer platanoides (aka: Norway maple)
Rubus ursinus (aka: California blackberry, California dewberry, California grapeleaf dewberry, Douglasberry, Pacific blackberry)
Salix lemmonii (aka: Lemmon's willow, Lemmon willow)
Salix planifolia (aka: Diamondleaf willow, Planeleaf willow)
Salix boothii (aka: Booth's willow)
Robinia pseudoacacia (aka: Black locust, False acacia, Yellow locust, White locust, Green locust, Post locust, Falsa acacia, Robinia)
Rhamnus cathartica (aka: Common buckthorn, European buckthorn, Dahurian buckthorn)
Astragalus (aka: Milkvetch, Locoweed, Goat's-thorn)
Populus tremuloides (aka: Quaking aspen, Trembling aspen, Aspen, American aspen, Mountain aspen, Golden aspen, Trembling poplar, White poplar, Popple, Alamo Blanco)
Rubus laciniatus (aka: Cutleaf blackberry, Evergreen blackberry, Slashed blackberry)
Salix lutea (aka: Yellow willow)
Salix geyeriana (aka: Geyer willow, Silver willow)
Allium schoenoprasum (aka: Chives)
Brassica napus (aka: Rapeseed)
Sinapis arvensis (aka: Charlock mustard, California rape, Charlock, Corn mustard, Canola, Kaber mustard, Rapeseed mustard)
Gleditsia triacanthos (aka: Honey locust, Honey shucks locust, Common honeylocust, Sweet bean locust)
Prunus pensylvanica (aka: Pin cherry, Fire cherry, Bird cherry)
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)
Prunus virginiana (aka: Chokecherry, Western chokecherry, Common chokecherry, Black chokecherry)
Salix glauca (aka: Grayleaf willow, Gray willow, Gray-leaved willow)
Salix brachycarpa (aka: Shortfruit willow, Barren-ground willow, Small-fruit sand dune willow, Small-fruit willow)
Rubus parviflorus (aka: Thimbleberry, Western thimbleberry)
Rubus armeniacus (aka: Himalayan blackberry, Rubus discolor, Rubus procerus)
Rubus idaeus (aka: Raspberry, Black-haired red raspberry, Brilliant red raspberry, American red raspberry, Red raspberry, Smoothleaf red raspberry, Wild raspberry, Wild red raspberry, Grayleaf raspberry)
Echium vulgare (aka: Viper's bugloss, Blueweed, Blue thistle)
Brassica rapa (aka: Field mustard, Common mustard, Wild mustard, Wild turnip, Forage turnip, Wild rutabaga, Birdsrape mustard, Rape mustard)
Asclepias syriaca (aka: Сommon milkweed, Butterfly flower, Silkweed, Silky swallow-wort, Virginia silkweed)
Agastache foeniculum (aka: Giant hyssop, Blue giant hyssop, Anise hyssop, Fragrant giant hyssop, Lavender giant hyssop)
Chamaenerion angustifolium (aka: Fireweed, Great willowherb, Rosebay willowherb, Saint Anthony's Laurel, French-willow)
Borago officinalis (aka: Borage, Starflower, Common borage, Cool-tankard, Tailwort)
Cucumis melo (aka: Cantaloupe, Rockmelon, Sweet melon, Spanspek, Honeydew melon, Honeymelon, Crenshaw, Casaba)
