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Montana Field Guide

Montana Field Guides

Flowering-rush - Butomus umbellatus

Noxious Weed: Priority 2A
Exotic Species (not native to Montana)

Global Rank: G5
State Rank: SNA
* (see State Rank Reason below)

Agency Status
MNPS Threat Rank:
C-value: 0

External Links

State Rank Reason (see State Rank above)
First collected in Montana in 1964. Known from the Flathead Drainage downstream to Noxon Reservoir; and Salmon Lake.
General Description
Perennial scapose herb from a fleshy rhizome. Herbage glabrous. Leaves mainly basal, 2-ranked, ascending to erect, linear, 4–8 mm wide. Inflorescence an umbel enclosed by 3 ovate, purplish bracts, reflexed at anthesis; pedicels unequal, 1–9 cm long; scape 3-angled, 50–100 cm. Flowers perfect, regular; sepals 3, green; petals 3, pinkish, 8–12 mm long; stamens 9; ovaries superior; pistils 6. Fruit many-seeded, beaked follicles, 8–10 mm long (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Flowering June-August

Range Comments
Introduced to much of northern U.S. and adjacent Canada; native to Eurasia. Known from Lake and Flathead counties (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Marshes, wetlands and slow-moving water along riverbanks.

Reproductive Characteristics
Reproduces and spreads by seeds and vegetatively via rhizomes and bulbils.

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Citation for data on this website:
Flowering-rush — Butomus umbellatus.  Montana Field Guide.  .  Retrieved on , from