More or less erect, branched, 3-6 dm, glabrous or glandular-puberulent above; lvs variable, mostly obovate to subrotund, sinuate-dentate, the principal veins arising near the base; lower lvs short-petioled, the upper sessile; fls bright yellow, 2.5-4.5 cm, the cor-throat constricted by the well developed, bearded palate; cal accrescent in fr, the lobes all broadly triangular, the upper median one the largest, the lateral ones tending to fold inward in fr; 2n=16, 28, 30, 32, 48, 56. Wet places; native mainly in the w. cordillera, occasionally escaped from cult. in our range. July, Aug. (M. langsdorfii). The cordilleran population is more variable than the cult. forms here described, often with smaller fls.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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Wiggins 1964, Kearney and Peebles 1969, Martin and Hutchins 1969
Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: Native annual or perennial herb, rarely stoloniferous but often rooting at the nodes; stems erect to lying down, simple or sparingly branched, 5-55 cm tall; usually more-or-less glabrous below and glandular-hairy in the inflorescence. Leaves: Opposite, petiolate below and sessile above, broadly ovate to orbicular, 15-55 mm long, 10-40 mm wide, with irregularly toothed margins; more-or-less glabrous. Flowers: Solitary from the leaf axils on stalks 1-6 cm long; calyx bell-shaped, ribbed, 6-16 mm long in flower (becoming inflated and to 20 mm long in fruit); corolla yellow, 9-23 mm long, two-lipped with the lower lip hairy and spotted with red, soon deciduous after anthesis. Fruits: Capsule oblong, 7-12 mm long, included in the inflated, more-or-less closed up calyx. Ecology: Found in wet areas, especially near streams; 1,000-9,500 ft (305-2895 m); flowers March-September. Distribution: Most of western N. Amer;, NM to CA and north to AL; south to s MEX, and in S. Amer. Notes: Always found in wet places, this is a large, but highly variable Mimulus, with big yellow, bilabiate flowers; can be distinguished vegetatively by its broader, generally glabrous leaves with teeth and its erect to decumbent habit. Host plant for Mylitta Crescent butterfly. Ethnobotany: Leaves and stems were used as flavor enhancers. Juice of leaves make a soothing poultice for minor burns and skin irritations. Yavapai use decoction for stomachache. Etymology: Mimulus means ape-flower, or a diminutive of the Latin minimus, a comic or mimic actor, because of the grinning corolla, while guttatus is from Latin meaning -a drop-like spot- which describes the red dots on both petals and sepals. Synonyms: Mimulus arvensis, M. bakeri, M. brachystylis, M. clementinus, M. cordatus, M. cuspidata, M. decorus, M. equinnus, M. glabratus var. ascendens, M. glareosus, M. grandiflorus, M. grandis, M. guttatus subsp. arenicola, M. guttatus subsp. arvensis, M. guttatu Editor: SBuckley 2010, FSCoburn 2015