Mimulus remains as a small genus of eastern North America and the Southern Hemisphere.

Species are found at elevations from oceanside to high mountains as well as a wide variety of climates, though most prefer wet areas such as riverbanks.

Erythranthe is a highly diverse genus with the characteristics unifying the various species being axile placentation and long pedicels.

[9][10] Some species produce copious amounts of aromatic compounds, giving them a musky odor (hence "musk-flowers").

[11] Erythranthe is used as food by the larvae of some Lepidoptera species, such as the mouse moth (Amphipyra tragopoginis), as a main part of their diet.

[12] Within the section Erythranthe, stems and leaves range from glabrous to hirsute, and are generally glandular.

Corollas are deciduous, relatively large (tube-throat 8–42 mm (0.3–1.7 in) long), and strongly red to purplish, magentarose, pink, or white, rarely yellow.

E. guttata is 5–80 cm (2–31 in) tall with disproportionately large 5–20 mm (0.2–0.8 in) long, tubular flowers.

The stem of Erythranthe can be either smooth or hairy, and this is known in a few species to be a trait determined by a simple allelic difference.

[20] At least E. lewisii is known to possess "flypaper-type" traps and is apparently protocarnivorous, supplementing its nutrients with small insects.

[22][23][24] The species that are subshrubs with woody stems were originally placed in the section Diplacus, and this was subsequently made a separate genus.

Diplacus is clearly derived from within Mimulus, broadly defined, and was not usually considered to be a separate genus.

In 1885, American botanist Edward Lee Greene classified Erythranthe as a section of Mimulus while adding E. lewisii and E.

[25][26] The genus Phryma (comprising only a single species), for which the family is named, is considerably different in morphology from all of the monkey-flowers.

[6][32] E. peregrina is an example of a successful naturally occurring hybrid that not only arose independently in two different locations, but is also a rare example of evolutionary recent allopolyploidization, complete chromosomal inheritance.

E. guttata is highly complex, with many variations apparently reflecting differences in geographic environment and elevation.

E. lewisii is pollinated by bees, primarily Bombus and Osmia, which feed on its nectar and transfer its pollen.

[6][46] It was previously reported that evidence strongly linking pollination preference to color differences between the species, but this has been disproven.

[6] Erythranthe parishii is also closely related to E. lewisii, but it has evolved in a different direction as a self-pollinated species with small flowers.

[52][53] Erythranthe nasuta evolved from E. guttata in central California between 200,000 and 500,000 years ago and since then has become primarily a self-pollinator.

[56] Genus members are also found in Baja California, Alaska, British Columbia, Nevada, Utah, Idaho, Montana, Wyoming, Colorado, Arizona, New Mexico, and to a lesser extent the midwestern states, northeastern states, Canada, and Latin America.

[59][60] Some species grow in dry areas, others in wet habitats, such as members of the section Simiolus, which are hydrophilic.

[56][61] Species are found at elevations from oceanside to high mountains as well as a wide variety of climates, though most prefer wet areas such as riverbanks.

The pests these genera are susceptible to include: gall midges, golden mealybugs, thrips, and seed bugs.

[62] Diseases they are susceptible to include: crown gall, aster yellows phytoplasma, impatiens necrotic spot virus (INSV), leaf spots, powdery mildew — especially Erysiphe brunneopunctata and Erysiphe cichoracearum, botrytis blight, pythium root rot, rusts, cucumber mosaic virus (CMV),[63] as well as mineral and nutrient deficiencies.

[66][67] Erythranthe species tend to concentrate sodium chloride and other salts absorbed from the soils in which they grow in their leaves and stem tissues.

[70] Erythranthe has been listed as one of the 38 plants that are used to prepare Bach flower remedies,[71] a kind of alternative medicine promoted for its effect on health.