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The Virtual WeedPatch
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Weed Identification: Plant Family

Learning weeds by plant families is one of the best ways to learn identification. Families often have common traits among different species that allow you to group weeds in your mind for easier ID. These family characteristics are also very helpful to begin ID of a new weed species.

Closely related to the plant family way of learning weed ID is the "species-group" concept discussed previously. Many of our most successful weed "species" are in fact a group of closely related, often inter-fertile, species. Learning these weed species-groups will aid you in learning weed ID.

Plant Family ----> Species-Group ----> Species ----> Variants


Composite (Compositae) Family


common cocklebur (Xanthium strumarium) summer annual
dandelion (Taraxacum officinale) perennial

The Thistle Species-Group:
-Canada thistle (Circium arvense) perennial
-Biennial Thistles:
bull thistle (Circium vulgare) biennial
musk thistle (Carduus nutans) biennial

The Ragweed Species-Group:
common ragweed (Ambrosia artimeisiifolia) summer annual
giant ragweed (Ambrosia trifida) annual


Dogbane (Apocynaceae) Family

hemp dogbane (Apocynum cannabinum) perennial


Grass (Graminaceae; Poaceae) Family

quackgrass (Elytrigia repens ) perennial
woolly cupgrass (Eriochloa villosa) summer annual
barnyardgrass (Echinochloa crus-galli) summer annual

The Panicum Species-Group:
wild proso millet (Panicum miliaceum) summer annual
fall panicum (Panicum dichotomiflorum) summer annual
witchgrass (Panicum capillare) summer annual

The Foxtail Species-Group:
green foxtail (Setaria viridis) summer annual
bristly foxtail (Setaria verticillata) summer annual
giant foxtail (Setaria faberi) summer annual
yellow foxtail (Setaria glauca) summer annual
knotroot foxtail (Setaria geniculata) summer annual

The Crabgrass Species-Group:
large crabgrass (Digitaria sanguinalis) summer annual
smooth crabgrass (Digitaria ischaemum) summer annual

The Sorghum Species-Group:
shattercane (Sorghum bicolor) summer annual
johnsongrass (Sorghum halpense) perennial
sorghum-almum (Sorghum almum) summer annual


Lambsquarters (Chenopodiaceae) Family

common lambsquarters (Chenopodium album) summer annual


Mallow (Malvaceae) Family

velvetleaf (Abutilon theophrasti) summer annual


Milkweed (Asclepiadaceae) Family

common milkweed (Asclepias syriaca) perennial


Mustard (Cruciferae) Family

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


Nightshade (Solanaceae) Family

jimsonweed (Datura stramonium) summer annual


Pigweed (Amaranthaceae) Family

The Pigweed Species-Group
redroot pigweed (Amaranthus retroflexus) summer annual
smooth pigweed (Amaranthus hybridus) summer annual
Powell pigweed (Amaranthus powellii) summer annual
spiny pigweed (Amaranthus spinosus) summer annual
tumble pigweed (Amaranthus albus) summer annual
prostrate pigweed (Amaranthus blitoides) summer annual
common waterhemp (Amaranthus rudis) summer annual
tall waterhemp (Amaranthus tuberculatus) summer annual
Palmer amaranth (Amaranthus palmeri) summer annual


Smartweed (Polygoneaceae) Family

The Polygonum Species-Group
-Knotweed Species-Group
prostrate knotweed (Polygonum aviculare) summer annual
erect knotweed (Polygonum erectum) summer annual
-Smartweed Species-Group
Pennsylvania smartweed (Polygonum pensylvanicum) summer annual
ladysthumb (Polygonum persicaria) summer annual




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