Pigweed / Amaranthus

Knotweed, Smartweed, Tearthumb (Polygonum)

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Knotweed, Smartweed, Tearthumb Genus Details

The Polygonum genus contains plants with simple, alternate leaves and numerous small flowers in spikes. Some are considered weeds and others make good border plants. This plant can grow to 3' tall. The latin name polygonum means "many joints".

Knotweed, Smartweed, Tearthumb Allergy Info

All Polygonum members can cause skin rash and some cause airborne allergy.

Knotweed, Smartweed, Tearthumb Pollen Description

No pollen description is currently available.

Species in This Genus

Allergenicity Legend:

Mild Allergen |

Moderate Allergen |

Severe Allergen |

Allergy Test Available

Knotweed, Smartweed, Tearthumb (Polygonum) is a genus of the POLYGONACEAE family.
This genus includes the following allergenic species:

Water Smartweed (Polygonum amphibium)

Allergens and Plants Search

Enter a full or partial species name to find more information on one of over 1200 potentially allergenic plants. For example, you can find chenopods searching on "cheno" (no quotes) as Latin Name.

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Knotweed, Smartweed, Tearthumb Genus Location

Allergies By County Map For Knotweed, Smartweed, Tearthumb

The shaded areas on the map indicates where the genus has been observed in the United States. Click the map to see a full scale version of these allergy areas.

- Native, observed in a county

- Introduced, observed in a county

- Rarely observed