Annual. Stems erect, usually branched, 2–10 cm. Herbage glabrate to glandular-puberulent. Leaves sessile, linear-lanceolate, serrate, 5–15 mm long. Flowers: calyx purplish, 3–5 mm long, ca. as long as the pedicel, teeth equal, up to 0.5 mm long; corolla yellow, 4–6 mm long, obscurely bilabiate, lobes subequal. Capsule 4–5 mm long (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
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.
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.
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.
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.
Vernally moist soil of grasslands and rocky slopes in the foothills and montane zones.
