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Montana Field Guide

Montana Field Guides

Brewer's Monkeyflower - Mimulus breweri

Status Under Review
Native Species

Global Rank: G5
State Rank: SNR
C-value: 7

Agency Status


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General Description
PLANTS: A small annual with erect, usually simple stems that grow from 2 to 1 cm tall. Plants have stalked gland (stipitate-glandular). Source: Lesica et al. 2012.

LEAVES: Leaves are simple, sessile, and arranged opposite on the stem. Leaf blades are narrowly lanceolate with smooth (entire) margins and 5 to 20 mm long. Source: Lesica et al. 2012.

INFLORESCENCE: Pairs of small flowers with long stems (pedicels) growing from the upper leaf axils. Purplish flowers are weakly bilabiate. Source: Giblin et al. [eds.] 2018; Lesica et al. 2012.

Mimulus is derived from the Latin word mime, meaning “actor” or “mimic,” and the male diminutive -ulus (Merrium-Webster 2019). This is most likely referring to the mask-like appearance of the flowers.

Diagnostic Characteristics
Montana has 5 native Mimulus species with purplish flowers, of which 2 are perennial and 3 are annual plants. In Montana Mimulus species have opposite, simple leaves, and in the axils of upper leaves grows pairs of stemmed flowers. Flowers have 5-petals and 5-sepals, are bilaterally symmetrical, and tubular.

Brewer's Monkeyflower-Mimulus breweri
*Habit: Plants are annuals, often less than 15 cm tall.
*Herbage: Stalked-glands (stipitate glandular).
*Leaves: Narrow blades (lanceolate) with entire margins (smooth), stemmed (petiolate), and 5-20 mm long.
*Flowers: The calyx is purplish. The corolla is 5-10 mm long, purple to red, and slightly bilabiate.
*Capsule: The mature capsule is 5-7 mm long.

Dwarf Purple Monkeyflower-Mimulus nanus
*Habit: Planta are annual, often less than 10 cm tall.
*Herbage: Glandular-puberulent.
*Leaves: Petiolate below and sessile above, oblanceolate, entire, and 5 to 15 mm long.
*Flowers: The corolla is 1-2 cm long, magenta, and bilabiate with a yellow-spotted palate.
*Capsule: The mature capsule is 7-11 mm long.

North Idaho Monkeyflower-Mimulus clivicola
*Habit: Plants are annuals, often less than 10 cm tall.
*Herbage: Glandular-pubescent.
*Leaves: Sessile, oblong, entire, and about 1 cm long.
*Flowers: The corolla is 10-15 mm long, purple and bilabiate with unequal lobes and a yellow-spotted palate.
*Capsule: The mature capsule is 5-8 mm long and tubular.

Square-stem Monkeyflower-Mimulus ringens
*Habit: Plants are mat-forming, rhizomatous perennials, often more than 15 cm tall.
*Herbage: None (glabrous).
*Leaves: Sessile, lanceolate to oblanceolate, serrate, and 2-8 cm long.
*Flowers: The corolla is 20-27 mm long, purple, and bilabiate with a bearded palate.
*Capsule: The mature capsule is 10-12 mm long.

Lewis’ Monkeyflower-Mimulus lewisii
*Habit: Plants are rhizomatous perennials, often more than 15 cm tall.
*Herbage: Almost glabrous (glabrate) to glandular-pubescent.
*Leaves: Sessile to subsessile, lanceolate to ovate, serrate, and 1-7 cm long.
*Flowers: The corolla is 3-5 cm long, bilabiate, pink-purple or magenta with a yellow and purple-spotted palate.
*Capsule: The mature capsule is 12-16 mm long.

Range Comments
Brewer's Monkeyflower can be found from British Columbia to Montana and south to California, Nevada, and Utah (Lesica et al. 2012).

Observations in Montana Natural Heritage Program Database
Number of Observations: 11

(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)

Brewer's Monkeyflower prefers vernally moist,sparsely vegetated soil of rock outcrops, streambanks, and avalanche slopes from the valleys to subalpine zones in Montana (Lesica et al. 2012).

The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus vagans, Bombus bifarius, Bombus centralis, Bombus flavifrons, and Bombus pensylvanicus (Thorp et al. 1983, Colla and Dumesh 2010).

Reproductive Characteristics
The mature flowers of Brewer's Monkeyflower have a 5 to 10 mm long, weakly bilabiate, purple to red corolla (Lesica et al. 2012). The calyx of mature flowers is purplish, 3 to 7 mm long, and has equal teeth of about 1mm long. The pedicels are 1-2 times longer than the calyx. Stigma tips are unequal.

The mature fruit of Brewer's Monkeyflower is 5 to 7 mm long (Lesica et al. 2012).

  • Literature Cited AboveLegend:   View Online Publication
    • Colla, S.R. and S. Dumesh. 2010. The bumble bees of southern Ontario: notes on natural history and distribution. Journal of the Entomological Society of Ontario 141:39-68.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Thorp, R.W., D.S. Horning, and L.L. Dunning. 1983. Bumble bees and cuckoo bumble bees of California (Hymenoptera: Apidae). Bulletin of the California Insect Survey 23:1-79.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
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Citation for data on this website:
Brewer's Monkeyflower — Mimulus breweri.  Montana Field Guide.  .  Retrieved on , from