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Methodology – Weed Species
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For perennial grass species such as quack grass and perennial herbaceous species such as Canada thistle, the number
of shoots rather than the number of plants was counted. For annual grasses, such as wild oats, and clumped
perennials, such as foxtail barley, a rooted individual was counted as a single plant whatever the number of tillers.
Volunteer crop plants were counted as weeds.
Weed Species
Any plant found in the field that could not be identified, or that the surveyor was unsure of, was tagged, pressed, and
submitted for identification. Infrequently occurring species were identified in this way. The common and botanical
names of 73 weeds found in 2009 are listed in Table 4.
Table 4. Common and scientific names of plants that appear in this report
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Common Name
Scientific Name
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Alfalfa
Medicago sativa
L.
Annual sow-thistle
Sonchus oleraceus
L.
Ball mustard
Neslia paniculata
(L.) Desv.
Barley
Hordeum vulgare
L.
Barnyard grass
Echinochloa crusgalli
(L.) P. Beauv.&
(includes western barnyard grass)
E. muricata
var.
microstachya
Wiegand
Black medick
Medicago lupulina
L.
Bluebur
Lappula squarrosa
(Retz.) Dumort.
Broad-leaved plantain
Plantago major
L.
Bull thistle
Cirsium vulgare
(Savi) Ten.
Canada thistle
Cirsium arvense
(L.) Scop.
Canola (Argentine)
Brassica napus
L.
Chickweed
Stellaria media
(L.) Vill.
Cleavers
Galium aparine
L.
Common burdock
Arctium minus
Bernh. subsp.
minus
Common groundsel
Senecio vulgaris
L.
Corn
Zea mays
L.
Corn spurry
Spergula arvensis
L.
Cow cockle
Vaccaria hispanica
(Mill.) Rauschert
Curled dock
Rumex crispus
L.
Dandelion
Taraxacum officinale
G. H. Weber ex Wiggers
Downy brome
Bromus tectorum
L.
Field bindweed
Convolvulus arvensis
L.
Field dock
Rumex pseudonatronatus
(Borbas) Murb.
Flixweed
Descurainia sophia
(L.) Webb ex Prantl
Foxtail barley
Hordeum jubatum
L.
Goat's-beard
Tragopogon dubius
Scop.
Green foxtail
Setaria viridis
(L.) P. Beauv.
Hemp-nettle
Galeopsis tetrahit
L.
Japanese brome
Bromus japonicus
Thunb. Ex Murray
Kochia
Kochia scoparia
(L.) Schrad.
Lamb's-quarters
Chenopodium album
L. &
(may include net-seeded lamb's-quarters)
C. berlandieri
var.
zschackei
(Murr) Murr ex Asch.
Millet
Panicum miliaceum
L or
Setaria italica
(L.) P. Beauv.
Narrow-leaved hawk's-beard
Crepis tectorum
L.
Oats
Avena sativa
L.
Pale smartweed
Polygonum lapathifolium
L. &
(includes green smartweed)
P. scabrum
Moench
Pasture sage (may include other wormwood species)
Artemisia frigida
Willd.
Perennial sow-thistle
Sonchus arvensis
L.
Persian darnel
Lolium persicum
Boiss. & Hohen. ex Boiss.
(Table continued on next page)