Montana Field Guide

PLANTS: A fibrous-rooted or slender taprooted annual that has erect stems reaching 4 to 12 cm high Plants have glandular villous hairs that are multi-celled. Source: Lesica et al. 2012.

LEAVES: Leaves are simple, sessile, and arranged opposite on the stem. Leaves have petioles with ovate blades that have dentate margins and are 4 to 12 mm long. Source: Lesica et al. 2012.

INFLORESCENCE: Small, yellow flowers grow on long stems (pedicels) from the upper leaf axils.

The specific epithet floribundus translates from new Latin to “flowering freely” (Merriam-Webster 2019). Mimulus is derived from the Latin word mime, meaning “actor” or “mimic,” and the male diminutive -ulus (Merriam-Webster 2019). This is most likely referring to the mask-like appearance of the flowers.

Floriferous Monkeyflower flowers from late spring to early fall (Nesom et al. 2012).

Many past reports of M. floribundus were mis-identified and are actually Mimulus ampliatus.

Montana has 14 native Mimulus species (Lesica et al. 2012). The following species share characteristics of being short annuals, often less than 15 cm tall, with yellow flowers.

Floriferous Monkeyflower-Mimulus floribundus
*Hairs: Stems and calyx with glandular-villous, usually multi-cellular (septate), but occasionally unicellular hairs.
*Leaves: Petiolate, mostly shorter than the leaf blades. Blades are ovate, not noticeably dentate, and 4-12 mm long.
*Flower Stem: In fruit the pedicel ascends or is curved, and is not pressed against the substrate.
*Corolla: 7-11 mm long, yellow, bilabiate with a larger lower lobe and a red-spotted palate.
*Calyx: 4-7 mm long. Teeth equal, 1 mm or less long.

Stalk-leaved Monkeyflower-Mimulus ampliatus
*Hairs: Stems and calyx glabrate to glandular pubescent. Hairs are single-celled (not septate).
*Leaves: Petiolate. Blades are ovate, dentate, 2-10 mm long.
*Flower Stem: Pedicel is 2-3 times as long as the calyx.
*Corolla: 10-15 mm long, yellow, flares open, strongly bilabiate, and lower lip is longest.
*Calyx: Purplish, 4-8 mm long. Teeth (or lobes) equal, about 0.5 mm long.

Short-flowered Monkeyflower-Mimulus breviflorus
*Hairs: Stems and calyx with glandular-puberulent. Hairs are single-celled (not septate).
*Leaves: Petiolate, usually longer than the calyx. Blades are narrowly elliptic, entire, and 5-10 mm long.
*Flower Stem: Pedicel is 1-3 times as long as the calyx.
*Corolla: 5-8 mm long, yellow, and slightly bilabiate with subequal lobes.
*Calyx: 3-5 mm long. Teeth about equal, 1 mm or less long.

Thinsepal Monkeyflower-Mimulus hymenophyllus
*Stems are generally more prostrate and at the basal nodes are sharply bent.
*Hairs: Stems and calyx with sparsely glandular-pubescent. Hairs are single-celled (not septate).
*Leaves: Long-petiolate. Petiole is mostly longer than the blade. Blades are ovate, dentate, and 4-12 mm long.
*Flower Stem: Pedicel of flower is 3-4 times longer than the calyx. In fruit the pedicel bends to form about a 90-degree angle with stem and is generally pressed against the substrate.
*Corolla: 7-20 mm long, yellow, and nearly regular.
*Calyx: 3-5 mmm long. Teeth about equal with rounded to ovate tips. About 1 mm long.

Short-flowered Monkeyflower-Mimulus suksdorfii
*Hairs: Stems and calyx glabrate to glandular-puberulent. Hairs are single-celled (not septate).
*Leaves: Sessile. Blades are narrowly elliptic, entire, and 5-10 mm long.
*Flower Stems: Calyx about as long as the pedicel.
*Corolla: 5-8 mm long, yellow, and slightly bilabiate with subequal lobes.
*Calyx: Purplish, 3-5 mm long. Teeth about equal, 0.5 mm or less long.
*Habitat: In drier habitats than most Monkeyflowers.

Common Large Monkeyflower-Mimulus guttatus
*Plants found in temporarily moist areas, may grow as short annuals while those in permanently moist areas tend to be taller perennials; Sometimes plants become stoloniferous (Lesica et al. 2012).
*Hairs: Stems and calyx glabrate to glandular-puberulent. Hairs are single-celled (not septate).
*Leaves: Petiole is short. Blades are ovate, serrate, and 0.5-9 cm long.
*Corolla: 15-40 mm long, yellow with red-spots, and strongly bilabiate with spreading lips.
*Calyx: 6-14 mm long. Teeth (or lobes) acute, 0.5-3 mm long, and unequal; the upper calyx lobe is largest.

Floriferous Monkeyflower prefers vernally moist cliffs and streambanks in valleys of Montana (Lesica et al. 2012).

ASSOCIATED SPECIES
In a study of Mimulus species of eastern Oregon, Floriferous Monkeyflower was found to prefer cover canopy species of Ponderosa Pine (Pinus ponderosa), Douglas Fir (Pseudotsuga menziesii), Western Hemlock (Tsuga heterophylla), cottonwood (Populus spp.), and willow (Salix spp.) (Meinke 1991).

ECOLOGICAL TOLERANCE
While tolerant of fluctuating temperature, grazing pressures, and other disturbances, Floriferous Monkeyflower is sensitive to moisture levels and may experience fluctuations correlating to annual precipitation levels (Meinke 1995). Due to its high degree of phenotypic plasticity, Floriferous Monkeyflower is able to tolerate a wider range of temperature conditions than species with less plasticity (Sheth et al. 2014). This range includes both ends of the spectrum, achieving greater tolerance of both higher and lower temperatures than other species. Floriferous Monkeyflower is also very tolerant of disturbance (Meinke 1995). Its high fecundity makes it a very effective colonizer that is able to disperse very efficiently by wind and water (Meinke 1995). It also withstands grazing pressures possibly due to its dense, glandular hairs (Meinke 1995).

POLLINATORS
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).

FLOWERS
The mature flowers of Floriferous Monkeyflower have a 7 to 11 mm long, yellow corolla that is moderately bilabiate with a larger lower lobe and a red-spotted palate (Lesica et al. 2012). The calyx is 4 to 7 mm long with equal length teeth that are up to 1 mm long. The pedicel is 2 to 3 times as long as the calyx.


FRUIT and SEEDS
Plants primarily self-pollinating (Meinke 1991). Mature fruits are ellipsoidal capsules, 3-6 mm long, and contain many seeds (Lesica et al. 2012). The calyx inflates as capsules develop. Upon dehiscing capsules the inflated calyx traps seeds, slowing their dispersal (Meinke 1991). This allows them to avoid mass germination and mortality due to unfavorable conditions (Meinke 1991).

In drought conditions, Floriferous Monkeyflower seedlings exhibit accelerated sexual maturation and reproduction (Meinke 1991). This, along with their evolved calyces, enables them to survive and reproduce in unpredictable environments (Meinke 1991).

While tolerant of fluctuating temperature, grazing pressures, and other disturbances, Floriferous Monkeyflower is sensitive to moisture levels and may experience fluctuations correlating to annual precipitation levels (Meinke 1995).

STATE THREAT SCORE REASON
Threat impact not assigned because threats in Montana are not known (MTNHP Threat Assessment 2021).