According to observations of naturalists and beekeepers.
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Echium vulgare — known as viper's bugloss and blueweed — is a species of flowering plant in the borage family Boraginaceae. It is native to most of Europe, and western and central Asia and it occurs as an introduced species in North America.
This plant is present in at least 52 states/provinces in this country.
It is a biennial or monocarpic perennial plant growing to 30–80 cm tall, with rough, hairy, oblanceolate leaves. The flowers start pink and turn vivid blue and are 15–20 mm in a branched spike, with all the stamens protruding. The pollen is blue but the filaments of the stamens remain red, contrasting against the blue flowers.
It flowers between June and August.
Acer negundo (aka: Boxelder, Western boxelder, Arizona boxelder, California boxelder, Texas boxelder, Interior boxelder, Violet boxelder)
Pyrus communis (aka: European pear, Common pear)
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)
Rubus spectabilis (aka: Salmonberry)
Salix discolor (aka: Pussy willow, American pussy willow, Glaucous willow, Large pussy willow)
Salix exigua (aka: Narrowleaf willow, Coyote willow)
Prunus cerasus (aka: Sour cherry, Tart cherry, Dwarf cherry, Montmorency cherry)
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)
Salix scouleriana (aka: Scouler's willow, Upland willow)
Acer circinatum (aka: Vine maple)
Prunus emarginata (aka: Bitter cherry)
Malus fusca (aka: Oregon crab, Oregon crab apple, Pacific crab apple, Western crab apple)
Salix arbusculoides (aka: Littletree willow)
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 macrophyllum (aka: Bigleaf maple, Big-leaf maple, Oregon maple)
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 amygdaloides (aka: Peachleaf willow, Peach leaf 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)
Salix lemmonii (aka: Lemmon's willow, Lemmon willow)
Salix planifolia (aka: Diamondleaf willow, Planeleaf willow)
Salix pulchra (aka: Tealeaf willow, Flatleaf willow, Flat-leaved willow, Paneleaf willow, Thin red willow)
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)
Salix alaxensis (aka: Feltleaf willow, Alaska willow)
Salix geyeriana (aka: Geyer willow, Silver willow)
Rhus glabra (aka: Smooth sumac, Common sumac, Rocky Mountain sumac, Red sumac, Western sumac, White sumac)
Salix richardsonii (aka: Richardson's willow, Woolly willow)
Allium schoenoprasum (aka: Chives)
Brassica napus (aka: Rapeseed)
Sinapis arvensis (aka: Charlock mustard, California rape, Charlock, Corn mustard, Canola, Kaber mustard, Rapeseed mustard)
Prunus pensylvanica (aka: Pin cherry, Fire cherry, Bird cherry)
Calendula officinalis (aka: Marigold, Calendula, Pot marigold, English marigold)
Prunus virginiana (aka: Chokecherry, Western chokecherry, Common chokecherry, Black chokecherry)
Prunus serotina (aka: Black cherry, Wild black cherry, Rum cherry, Mountain black cherry, Wild cherry)
