Flowering rush

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

Butomus umbellatus

Colorado noxious weed · List A — Eradicate. CO-rules-2025

Uncommon in Colorado. All populations are designated for eradication statewide. This is a management category, separate from danger ratings. Category source · What the lists mean.

Small fragments spread aquatic colonies. Exposure help.

Identification caveat: Grass-like aquatic plants may not be flowering when found. Leaf bases and submerged structures matter for identification.

Still researching this plant

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

Butomus umbellatus: A cluster of pale pink flowers and buds held on radiating stalks beside open water. — **flowering umbel** — A cluster of pale pink flowers and buds held on radiating stalks beside open water.
Jacek Pietruszewski · CC BY 4.0
Photo source and identification
Original record · Original image
Source scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination.
iNaturalist large server-resized image; no local crop, colour change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop.

Butomus umbellatus: Open pale pink flowers showing six floral segments and red-tipped reproductive structures. — **flower detail** — Open pale pink flowers showing six floral segments and red-tipped reproductive structures.
Jacek Pietruszewski · CC BY 4.0
Photo source and identification
Original record · Original image
Source scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination.
iNaturalist large server-resized image; no local crop, colour change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop.

Butomus umbellatus: Flowering stems rising above narrow shoreline leaves beside a waterbody. — **habit** — Flowering stems rising above narrow shoreline leaves beside a waterbody.
Jacek Pietruszewski · CC BY 4.0
Photo source and identification
Original record · Original image
Source scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination.
iNaturalist large server-resized image; no local crop, colour change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop.

Recognize

An aquatic perennial with slender leaves, triangular leaf bases and clusters of pale pink flowers on tall stalks. WA-flowering-rush

Plants & habitat

Rhizome fragments and small vegetative bulbils enable spread. Casual digging can release propagules into the water; obtain a site-specific management plan. WA-flowering-rush

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

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

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

This is a statewide eradication priority. Contact your county weed program promptly for identification and an approved management and disposal plan. CO-rules-2025

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.
WA-flowering-rush — Flowering Rush, Washington State Noxious Weed Control Board. Accessed 2026-09-07T01:08:59+00:00. Locator: Identification, ecological impacts, management; Washington legal class not applied to Colorado.
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.