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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

Cashew Family (Anacardiaceae) Family

poison ivy (Rhus radicans) woody perennial

Composite (Compositae) Family

common cocklebur (Xanthium strumarium) summer annual
dandelion (Taraxacum officinale) perennial
horseweed (Conyza canadensis) summer annual
common sunflower (Helianthus annuus) summer annual

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

Gourd (Curcurbitaceae) Family

[bur cucumber (Sicyos angulatus) summer annual]

Grass (Graminaceae; Poaceae) Family

quackgrass (Elytrigia repens ) perennial
wirestem muhly (Muhlenbergia frondosa) perennial
[woolly cupgrass (Eriochloa villosa) summer annual]
barnyardgrass (Echinochloa crus-galli) summer annual
volunteer corn (Zea mays) summer annual
[field sandbur (Cenchrus incertus) summer annual, biennial]
[foxtail barley (Hordeum jubatum) perennial]

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

[The Bromegrass Species-Group]:
downy brome (Bromus tectorum) winter annual, summer annual
smooth brome (Bromus inermis) perennial

Hemp (Cannabaceae) Family

wild hemp, marijuana (Cannabis sativa; Cannabis indica) summer annual

Lambsquarters (Chenopodiaceae) Family

common lambsquarters (Chenopodium album) summer annual
[kochia (Kochia scoparia) annual]

Legume (Leguminosae; Fabaceae) Family

[black medic (Medicago lupulina) annual, biennial, perennial]

[Sweetclover species-group:]
yellow sweet clover (Melilotus officinalis) annual, biennial, perennial
white sweet clover (Melilotus alba) annual, biennial, perennial

Loosestrife (Lythraceae) Family

[purple loosestrife (Lythrum salicaria) perennial]

Mallow (Malvaceae) Family

velvetleaf (Abutilon theophrasti) summer annual
[venice mallow (Hibiscus trionum) summer annual]

Milkweed (Asclepiadaceae) Family

common milkweed (Asclepias syriaca) perennial

Mint (Labiatae) Family

[catnip (Nepeta cataria) perennial]

Morningglory (Convolvulaceae) Family

[ivy leaf morningglory (Ipomoea hederaceae) summer annual]

Bindweed species-group:
field bindweed (Convolvulvus arvensis) perennial
hedge bindweed (Calystegia sepium) perennial

Mustard (Cruciferae) Family

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

Nightshade (Solanaceae) Family

jimsonweed (Datura stramonium) summer annual

The Nightshade Species-Group:
eastern black nightshade (Solanum ptycanthum) summer annual
bitter nightshade (Solanum dulcamara) 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

Plantain (Plantaginaceae) Family

Plantain species-group:
Blackseed plantain (Plantago rugelii) perennial
Broadleaf plantain (Plantago major) perennial
Buckhorn plantain (Plantago lanceolata) perennial

Purslane (Portulacaceae) Family

purslane (Portulaca oleracea) summer annual

Rose (Rosaceae) Family

[multiflora rose (Rosa multiflora) perennial shrub

Sedge (Cyperaceae) Family

yellow nutsedge (Cyperus esculentus) perennial

Smartweed (Polygoneaceae) Family

The Polygonum Species-Group
-wild buckwheat (Polygonum convolvulvus) summer annual
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
-swamp smartweed (Polygonum coccineum) perennial

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