Erythranthe is a genus of flowering plants in the lopseed family (Phrymaceae, order Lamiales) commonly known as monkey-flowers or musk-flowers. The common name "monkey-flower" refers to the tubular, bilabiate corolla, whose face is said to resemble that of a small monkey; "musk-flower" refers to the musky scent produced by some members of the group. The genus name itself comes from the Greek erythros, meaning red, and anthos, meaning flower — a nod to the brightly coloured corollas of the type species, Erythranthe cardinalis.
Most current treatments accept around 111 to 120 species in the genus, organised into roughly twelve sections, making Erythranthe by far the largest segregate from the once-broadly-circumscribed Mimulus. The genus was first erected by the French botanist Édouard Spach in 1840 but spent most of the twentieth century absorbed into Mimulus as a section. In 2012, Barker, Nesom, Beardsley, and Fraga used DNA evidence to formally resurrect Erythranthe as a distinct genus, defined in part by axile placentation and long flower pedicels, leaving Mimulus in the strict sense reduced to about seven species.
The centre of diversity for Erythranthe is western North America: over 80% of the species occur in California, Oregon, and Washington, with additional ranges extending north to Alaska and British Columbia, east through the Rocky Mountains, south into Latin America, and across the Pacific into eastern Asia. Most species are herbaceous and tied to moist or wet ground — stream banks, seeps, springs, and even shallow standing water — although a handful tolerate drier, rocky, or specialised substrates. Elevation ranges run from sea level to alpine meadows above 3,500 metres.
A small but important subset of the genus is in cultivation. Horticultural monkey-flowers — long sold under the older name Mimulus — derive mainly from E. guttata and E. lutea, with E. cuprea contributing many named cultivars on its own. Several species are also valued in native-plant gardening and habitat restoration. E. guttata in particular has become one of the most heavily studied plant model organisms outside the major crop systems, underpinning research on ecological adaptation, pollinator-driven speciation, and floral evolution.
Etymology
The genus name Erythranthe is built from two Greek roots: erythros, meaning red, and anthos, meaning flower — a direct reference to the brightly coloured corollas typified by Erythranthe cardinalis, the scarlet monkey-flower that Spach designated as the type. In English, members of the genus are most often called monkey-flowers, because the gaping, bilabiate corolla is said to resemble a small monkey's face, or musk-flowers, in reference to the musky scent produced by some species.
Distribution
Erythranthe is overwhelmingly a western North American genus. More than 80% of its species are found in California, Oregon, and Washington, with additional native presence north into British Columbia and Alaska, east through the Rocky Mountains, and south into Latin America. A smaller number of species occur in eastern Asia, giving the genus an amphi-Pacific footprint within the broader Phrymaceae family, whose centres of diversity are western North America and Australia. In the southwestern United States, regional herbarium portals such as SEINet document over fifty Erythranthe taxa from Arizona and New Mexico alone, including narrowly endemic limestone and sand specialists like E. calciphila and E. arenicola. The widespread E. guttata occupies an exceptionally broad range, growing from sea level to about 12,000 feet across western North America.
Ecology
Most Erythranthe species are herbs of moist to wet ground — stream banks, seeps, springs, meadows, and the margins of standing water — and the genus as a whole has comparatively low drought resistance. That habitat preference does not prevent considerable ecological breadth: species occupy environments ranging from coastal lowlands to alpine zones, and the widespread E. guttata is recorded from California chaparral, desert oases, alpine meadows, and even the geyser fields of Yellowstone. Flowers are tubular and bilaterally symmetric with touch-sensitive bilamellar stigmas that close on contact with a pollinator, a feature shared across Phrymaceae. Within the genus, pollination syndromes vary sharply between closely related species — for example, E. cardinalis is hummingbird-pollinated while its sister E. lewisii is bee-pollinated — which has made Erythranthe a textbook system for studying pollinator-driven floral evolution.
Cultivation
A small but commercially significant subset of Erythranthe is grown ornamentally. Roughly sixteen species across Phrymaceae are in cultivation; within Erythranthe, the bulk of garden material traces back to E. guttata and E. lutea, with E. cuprea contributing ten or more named cultivars on its own. Six species — including E. cardinalis, E. guttata, E. lutea, and E. cuprea — are considered of special horticultural importance. Plants are still widely sold under the older name "Mimulus," reflecting their long pre-2012 history in the nursery trade, and are used both in conventional bedding-style plantings and in native-plant and habitat-restoration projects across western North America.
Conservation
Conservation status varies widely across Erythranthe. Wikipedia reports that at least 25 species are listed as threatened on the IUCN Red List, reflecting how many members of the genus are narrow endemics tied to specific seeps, calcareous outcrops, or other restricted habitats. By contrast, the most widespread species, E. guttata, is rated secure by NatureServe. The genus does not appear in the IUCN Global Invasive Species Database, which has no Erythranthe entries on file.
Cultural Uses
Beyond ornamental horticulture, a few Erythranthe species have minor food uses. The leaves of E. guttata are edible raw or cooked and have been used historically as a salad-lettuce substitute, though they are slightly bitter. The widespread cultivation of monkey-flowers — long marketed under the trade name "Mimulus" — also forms part of the broader cultural footprint of the genus in western gardens.
History
Erythranthe was first described by the French botanist Édouard Spach in 1840 and is still cited in GBIF as Erythranthe Spach, with an alternative authority of (L.) G.L. Nesom reflecting later nomenclatural work. In 1885, the genus was subsumed into Mimulus as a section, and it remained there for over a century. The 2012 paper by Barker, Nesom, Beardsley, and Fraga — "A Taxonomic Conspectus of Phrymaceae: A Narrowed Circumscription for Mimulus, New and Resurrected Genera, and New Names and Combinations" (Phytoneuron 39: 1–60) — used molecular evidence to formally resurrect Erythranthe, transferring 111 former Mimulus species (those with axile placentation and long pedicels) into it and leaving Mimulus in the strict sense with only about seven species.
Taxonomy Notes
Erythranthe sits in family Phrymaceae (Lopseed family), order Lamiales, with Erythranthe cardinalis as the type species. The GBIF backbone accepts Erythranthe Spach (nubKey 3171742) and also recognises Erythranthe (L.) G.L. Nesom as an accepted entry, listing 174 descendant taxa in the genus overall. Most recent treatments cite roughly 111 to 120 species organised into about twelve sections; Phrymaceae as a whole contains about 210 species in 13 genera, of which Erythranthe and Diplacus are by far the largest. Family-level diagnostic traits shared by Erythranthe include tubular five-lobed calyces, touch-sensitive bilamellar stigmas, and loculicidal capsules.
