Yellow sweetclover

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

Melilotus officinalis

Common introduced weed · not on state Lists A/B/C. C-floristic-2020 CO-rules-2025

Moldy sweetclover hay can cause dangerous bleeding. Exposure help.

Still researching this plant

This is a sourced working profile. Evidence is incomplete for People, Dogs & cats, Other animals. 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.

Yellow sweetclover: small yellow pea-like flowers hang along a narrow elongated raceme. — **flower** — Small yellow pea-like flowers hang along a narrow elongated raceme.
Isidre blanc · CC BY-SA 4.0
Photo source and identification
Original record · Original image
Source page scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination. Source-identified M. officinalis. Related yellow-flowered sweetclovers require reproductive characters for confident determination; flower color by itself is not species-specific.
Wikimedia server-resized derivative, reduced from the original; no crop, color change, upscaling, or generative editing. Gallery display preserves the full image; catalog preview may use a CSS crop.

Yellow sweetclover: a branching leafy plant with many slender yellow flower racemes at a path edge. — **habit** — A branching leafy plant with many slender yellow flower racemes at a path edge.
Rasbak · CC BY-SA 3.0
Photo source and identification
Original record · Original image
Source page scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination. Source-identified M. officinalis. Related yellow-flowered sweetclovers require reproductive characters for confident determination; flower color by itself is not species-specific.
Wikimedia server-resized derivative, reduced from the original; no crop, color change, upscaling, or generative editing. Gallery display preserves the full image; catalog preview may use a CSS crop.

Yellow sweetclover: compound leaves with three finely toothed leaflets along upright branching green stems. — **foliage** — Compound leaves with three finely toothed leaflets along upright branching green stems.
Rasbak · CC BY-SA 3.0
Photo source and identification
Original record · Original image
Source page scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination. Source-identified M. officinalis. Related yellow-flowered sweetclovers require reproductive characters for confident determination; flower color by itself is not species-specific.
Wikimedia server-resized derivative, reduced from the original; no crop, color change, upscaling, or generative editing. Gallery display preserves the full image; catalog preview may use a CSS crop.

Identification

An upright, usually biennial legume with three leaflets and elongated clusters of small yellow flowers. Fresh flower color separates it from white sweetclover. N-melilotus-officinalis F-melilotus

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

Improperly cured or moldy sweetclover hay can develop compounds that impair clotting, causing severe internal bleeding. Diets dominated by sweetclover also carry a livestock bloat risk. These findings do not establish pet exposure limits. F-melilotus

Evidence scope: Sweetclover group evidence.

Plants & habitat

It fixes nitrogen and feeds pollinators, but can spread beyond plantings. Its deep taproot helps established plants tolerate dry conditions. N-melilotus-officinalis

Management & timing

Prevent flowering and reseeding where unwanted. Have suspect hay assessed before feeding it. C-descriptions F-melilotus

Evidence scope: Management synthesis.

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

C-floristic-2020 — Colorado Floristic Quality Assessment: 2020 Update, Colorado Natural Heritage Program, Colorado State University. Accessed 2026-09-07T02:27:33+00:00. Locator: Appendix B, Colorado species list: scientific name and native/non-native fields.
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.
N-melilotus-officinalis — Melilotus officinalis, NC State Extension. Accessed 2026-09-07T02:23:11+00:00. Locator: Description, identification attributes and plant problems; toxicity section where present.
F-melilotus — White and yellow sweetclover, USDA Forest Service, Fire Effects Information System. Accessed 2026-09-07T02:26:14+00:00. Locator: Named species or genus; identification, distribution and hazard sections where available.
C-descriptions — Weed descriptions, Colorado State University Extension. Accessed 2026-09-07T00:24:02+00:00. Locator: Species entries.
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 02:46:00Z · Source checks dated separately in the references.