Mayweed chamomile

Discuss this plant with the guide — choose this profile as a possible match and prepare your observations for Colorado Plants & Practical Care.

Anthemis cotula

Colorado noxious weed · List B — Stop the spread. CO-rules-2025

Established in some areas. Requirements vary by location: eradication, containment or suppression to stop further spread. This is a management category, separate from danger ratings. Category source · What the lists mean.

Crop weed with unpleasant-smelling foliage. Exposure help.

Identification caveat: Do not substitute Roman chamomile (Anthemis nobilis / Chamaemelum nobile) toxicology. The retrieved NC State URL described a different plant and was excluded.

Still researching this plant

This is a sourced working profile. Evidence is incomplete for People, Dogs & cats. Identification and source-photo limits are explained below. Independent botanical and veterinary review is pending. Uncertainty is not a finding that the plant is safe.

Three views of this plant

Source-identified reference photographs; these are not a complete identification key. A source location outside Colorado does not establish local occurrence.

**flowers** — Mayweed chamomile heads with white rays around raised yellow centers.
NY State IPM Program at Cornell University from New York, USA · CC BY 2.0
Photo source and identification
Original record · Original image
Source-identified photograph with visual consistency check Mayweed chamomile. For more information on identification and control, visit <a href=" http://turfweeds.cals.cornell.edu/plant/identify/157 " rel="nofollow">turfweeds.cals.cornell.edu/plant/identify/157</a> Source labeling and visible consistency checked; not an independent specimen determination.
Wikimedia-generated thumbnail rescaling only; downloaded bytes unchanged. Gallery display preserves the full image; the catalog preview uses a CSS crop.

**habit** — A broad, branching mayweed chamomile plant covered with numerous small white-and-yellow flower heads.
NY State IPM Program at Cornell University from New York, USA · CC BY 2.0
Photo source and identification
Original record · Original image
Source-identified photograph with visual consistency check Mayweed chamomile. For more information on identification and control, visit <a href=" http://turfweeds.cals.cornell.edu/plant/identify/157 " rel="nofollow">turfweeds.cals.cornell.edu/plant/identify/157</a> Source labeling and visible consistency checked; not an independent specimen determination.
Wikimedia-generated thumbnail rescaling only; downloaded bytes unchanged. Gallery display preserves the full image; the catalog preview uses a CSS crop.

**foliage** — A leafy mayweed chamomile shoot with finely divided green foliage.
Andrianl · CC0
Photo source and identification
Original record · Original image
Source-identified photograph with visual consistency check Stinking chamomile ( Anthemis cotula ) in New Zealand Source labeling and visible consistency checked; not an independent specimen determination.
Wikimedia-generated thumbnail rescaling only; downloaded bytes unchanged. Gallery display preserves the full image; the catalog preview uses a CSS crop.

Recognize

A bushy annual with finely divided leaves, white ray flowers around yellow centers and a strong, unpleasant odor. UC-mayweed

Plants & habitat

Colonizes disturbed ground and agricultural sites; seed production sustains infestations. UC-mayweed

People

The reviewed sources do not establish species-specific ingestion effects or a safe exposure amount for people. Missing evidence does not establish safety.

Dogs & cats

The reviewed sources do not establish species-specific ingestion effects or a safe exposure amount for dogs or cats. Missing evidence does not establish safety.

Other animals

Cornell reports livestock avoidance and milk taint after consumption. That is not a quantified pet-poisoning assessment. K-chamomiles

Before taking action

Confirm identification and the requirements of your county weed program. For chemical treatment, follow the current product label, including restrictions around animals and water. S27

References

CO-rules-2025 — Colorado Noxious Weed Act rules, 8 CCR 1206-2, Colorado Secretary of State / Department of Agriculture. Accessed 2026-09-07T01:07:48+00:00. Locator: Parts 3.1, 4.1, 5.1; management provisions; effective May 15, 2025.
UC-mayweed — Mayweed chamomile, University of California Statewide IPM. Accessed 2026-09-07T01:16:19+00:00. Locator: Species identity, description, ecological and exposure evidence; verify group scope.
K-chamomiles — Chamomiles, Cornell University College of Agriculture and Life Sciences. Accessed 2026-09-07T01:16:19+00:00. Locator: Species identity, description, ecological and exposure evidence; verify group scope.
S27 — 2103 – Colorado Noxious Weeds, PlantTalk Colorado · CSU Extension. Accessed 2026-09-07T00:23:57+00:00. Locator: List A, B and C management categories.

Content revised 2026-09-07 03:50:00Z · Source checks dated separately in the references.