According to observations of naturalists and beekeepers.
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Cirsium arvense is a perennial species of flowering plant in the family Asteraceae, native throughout Europe and western Asia, northern Africa, and widely introduced elsewhere. The standard English name in its native area is creeping thistle. It is also commonly known as Canada thistle and field thistle.
Cirsium arvense was accidentally introduced to North America in the 1600s and is designated as a noxious weed in 43 states. It occurs from Alaska east to the Northwest Territories, Quebec, and Newfoundland and south to California, New Mexico, Kansas, Arkansas, and North Carolina.
This plant is present in at least 54 states/provinces in this country.
Cirsium arvense (Canada thistle) has a deep and wide-spreading root system with a slender taproot and far-creeping lateral roots. It often forms large patches, and individual clones may reach 35 m in diameter. Most Canada thistle roots are in the top 0.2-0.6 m of soil, but roots can extend as deep as 2-6.75 m.
Canada thistle has slender aerial shoots with leafy stems reaching 0.3-2 m tall. Leaves are 3-18 cm long and 0.5-6 cm wide. Canada thistle leaf morphology (texture, hairiness, loving, and spininess) can vary considerably, even within a geographical region. Canada thistle has numerous above-ground branches that bear several, small flowerheads (1-2 cm in diameter) in clusters. Seeds are 2.4-5 mm long, and 1 mm in diameter with a pappus of feathery bristles.
Plants develop new roots and underground shoots in January and begin to elongate in February. New shoots from established Canada thistle plants begin to emerge when the average weekly temperature reaches 41 degrees Fahrenheit (5 °C), with optimum emergence after temperatures are at least 46 degrees Fahrenheit (8 °C). Plants remain short until long days trigger flowering and stem elongation, normally in May and June, or about 3 weeks after emergence. When soil is warm and temperatures are moderate (as in fall) Canada thistle grows vigorously.
Acer saccharinum (aka: Silver maple, Soft maple)
Aronia arbutifolia (aka: Red chokeberry)
Pyrus communis (aka: European pear, Common pear)
Acer negundo (aka: Boxelder, Western boxelder, Arizona boxelder, California boxelder, Texas boxelder, Interior boxelder, Violet boxelder)
Salix nigra (aka: Black willow, Swamp willow, Southwestern black willow, Gulf black willow, Scythe-leaved willow)
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 cerasus (aka: Sour cherry, Tart cherry, Dwarf cherry, Montmorency 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)
Ulmus americana (aka: American elm, White elm, Water elm, Soft elm, Florida elm)
Malus domestica (aka: Pyrus pumila, Malus pumila, Apple)
Acer platanoides (aka: Norway maple)
Acer saccharum (aka: Sugar maple, Rock maple, Hard maple)
Celtis occidentalis (aka: Common hackberry, Bastard elm, Nettle-tree, Northern hackberry)
Acer pensylvanicum (aka: Striped maple, Moosewood, Goosefoot maple, Whistlewood)
Rubus canadensis (aka: Smooth blackberry, Thornless blackberry, Canadian blackberry, Smooth highbush blackberry)
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)
Catalpa speciosa (aka: Northern catalpa, Hardy catalpa, Western catalpa, Cigar tree, Catawba-tree, Bois chavanon)
Acer spicatum (aka: Mountain maple, Low maple, Moose maple, Water maple, Plaine batarde, Fouereux)
Astragalus (aka: Milkvetch, Locoweed, Goat's-thorn)
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)
Rhus glabra (aka: Smooth sumac, Common sumac, Rocky Mountain sumac, Red sumac, Western sumac, White sumac)
Brassica napus (aka: Rapeseed)
Allium schoenoprasum (aka: Chives)
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)
Aronia melanocarpa (aka: Black chokeberry, Rowan, Mountain Ash, Sorbus)
Prunus serotina (aka: Black cherry, Wild black cherry, Rum cherry, Mountain black cherry, Wild cherry)
Prunus pensylvanica (aka: Pin cherry, Fire cherry, Bird cherry)
Robinia pseudoacacia (aka: Black locust, False acacia, Yellow locust, White locust, Green locust, Post locust, Falsa acacia, Robinia)
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)
Calendula officinalis (aka: Marigold, Calendula, Pot marigold, English marigold)
Rhamnus cathartica (aka: Common buckthorn, European buckthorn, Dahurian buckthorn)
Salix planifolia (aka: Diamondleaf willow, Planeleaf willow)
Tilia americana (aka: American basswood, Basswood, Linden)
