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Cankerweed

Nabalus serpentarius

Last reviewed: October 2026

Cankerweed (Nabalus serpentarius)
Photo: (c) Sean Bloom, some rights reserved (CC BY), uploaded by Sean Bloom

Toxicity unknown

Cankerweed (Nabalus serpentarius) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.

Light

part shade

Water

medium

Size

24"–60" H × 12"–24" W

Bloom

Jul, Aug, Sep

Native to

AL, CT, DE, FL and 15 more states

Pollinators

bees, butterflies, moths

Before you buy

Your city may pay you to plant this

Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 459 programs across 44 states, each with a link to the provider and the date we last checked it.

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Browse plants for this ecoregion

PiedmontNortheastern Coastal ZoneMiddle Atlantic Coastal PlainNorthern PiedmontSoutheastern PlainsBlue RidgeRidge and ValleyEastern Temperate ForestsCentral AppalachiansWestern Allegheny PlateauInterior PlateauSouthern Coastal PlainAtlantic Coastal Pine Barrens

Nodding rattlesnakeroot is a tall native wildflower that produces delicate drooping clusters of small white or pale yellow flowers from summer into fall. This woodland perennial thrives in partial shade and forms clumps of leafy stems that can reach up to 5 feet tall.

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In an HOA neighborhood

Cankerweed takes more care to keep looking intentional in a front yard. Maintenance level: low. Consider it for backyard or mid-zone beds rather than the street edge.

Works well in: backyard only.

  • Very tall height appears wild and unmanicured
  • Can look weedy when dormant
  • Informal woodland appearance doesn't fit typical HOA aesthetics

Wildlife value

The flowers attract bees, butterflies, and moths during the long blooming period from July through September. Seeds provide food for birds in fall and winter.

Common questions

How much sun does Cankerweed need?
Cankerweed grows best in part shade conditions.
When does Cankerweed bloom?
Cankerweed blooms in July, August, and September.
Where is Cankerweed native?
Cankerweed (Nabalus serpentarius) is native to AL, CT, DE, FL and 15 more states, per vouchered herbarium specimen records and regional native plant society lists.
What pollinators does Cankerweed attract?
Cankerweed draws bees, butterflies, and moths.
Is Cankerweed HOA-friendly?
Cankerweed takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

Native range data from vouchered herbarium specimen records and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

If something looks wrong

Common plant problems, and what to check first

These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.

See all plant problem guides

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