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The Virtual WeedPatch
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leafID.html

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Weed Identification: Leaf Shape & Stems

Weed identification using mature plant leaf shapes and stem characteristics is often the easiest way to learn for new students. Unfortunately, by the time the time plants are mature to reveal these features, the ball game is over: they have competed too long in a crop and yield losses have already occurred.

Proceed through each of the weed species below:

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Composite (Compositae) Family

dandelion (Taraxacum officinale) Perennial
common cocklebur (Xanthium strumarium) Summer annual

Ragweed species-group:
-giant ragweed (Ambrosia trif
-common ragweed (Ambrosia artimeisiifolia) Summer annual

Thistle species-group:
-Canada thistle (Circium arvense) Perennial
-biennial thistles:
--musk thistle
--bull thistle (Circium vulgare) biennial

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Dogbane (A ) Family

hemp dogbane

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Grass (Graminaceae; Poaceae) Family

quackgrass (Elytrigia repens ) Perennial
woolly cupgrass (Eriochloa villosa) summer annual
barnyardgrass

Foxtail species-group:
-bristly foxtail (Setaria verticillata) summer annual
-green foxtail (Setaria viridis) Summer annual
-giant foxtail (Setaria faberi) Summer annual
-yellow foxtail (Setaria glauca) Summer annual

Panicum species-group:
-wild proso millet (Panicum mileaceum) Summer annual
-fall panicum
-witchgrass

Crabgrass species-group:
-large crabgrass (Digitaria sanguinalis) Summer annual
-smooth crabgrass (Digitaria ischaemum) Summer annual
woolly cupgrass (Eriochloa villosa) summer annual

Sorhum species-group:
-johnsongrass
-sorghum-almum
-shattercane

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Lambsquarters (Chenopodiaceae) Family

common lambsquarters (Chenopodium album) Summer annual

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Mallow (Malvaceae) Family

velvetleaf (Abutilon theophrasti) Summer annual

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Milkweed (Asclepiadaceae) Family

common milkweed

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Mustard (Cruciferea) Family

field pennycress (Thlaspi arvense) Winter annual
shepard's purse (Capsella bursa-pastoris) Annual/Winter annual
wild mustard (Sinapis arvensis) annual/winter annual

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Nightshade ( ) Family

jimsonweed

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Pigweed (Amaranthaceae) Family

Pigweed species-group
-redroot pigweed

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Smartweed (Polygoneaceae) Family

Knotweed species-group:
prostrate knotweed (Polygonum aviculare) Summer annual
erect knotweed

Smartweed species-group:
-Pennsylvania smartweed
-Ladysthumb

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