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Montana Field Guide

Montana Field Guides

Watershield - Brasenia schreberi

Species of Concern

Global Rank: G5
State Rank: S1S2
* (see State Rank Reason below)

Agency Status
MNPS Threat Rank: 4
C-value: 9

External Links

State Rank Reason (see State Rank above)
Restricted in Montana to shallow waters in the valleys of the northwest corner of the state where it is known from eight occurrences, including six relatively high quality populations. Potential threats to the species include boating activity, aquatic weeds, and several populations are subject to runoff from adjacent agricultural fields, though it is uncertain if this has negatively impacted any populations.
General Description
Watershield is a rhizomatous perennial aquatic herb with branches which rise through the water, floating leafblades (lily pads), and emergent flowers. The leaves have long petioles attached alternately to the branches and centrally to the undersides of the floating leaf blades. The broadly elliptic to oval leaf blades are 4-12 cm long and 3-8 cm wide. Solitary flowers are held just above the water on long peduncles. The flowers usually have 3 sepals and 3 petals which are similar, translucent reddish-purple colored, linear to lance-shaped, and 1-1.5 cm long. There are 4-14 pistils and 12-36 purplish stamens which are about the same length as the petals and sepals. The leathery, beaked fruits are 6-8 mm long and mature underwater.

Flowering in August.

Diagnostic Characteristics
Distinguished from other water lilies (Nuphar and Nymphea) by its relatively small, purplish, many pistilled flowers and by its relatively small, truly peltate (with petiole attached to the center of the blade) leaves.

Species Range

Range Comments
Most of North America, widespread in other parts of the world except Europe. Sparse.

Summary of Observations Submitted for Montana
Number of Observations: 36

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Shallow water of lakes, sloughs, and slow-moving rivers in the valley zone.

Ecological Systems Associated with this Species
  • Commonly Associated with these Ecological Systems
    Wetland and Riparian Systems

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Citation for data on this website:
Watershield — Brasenia schreberi.  Montana Field Guide.  .  Retrieved on , from