Erythranthe Spach (syn.: Mimulus L. section Erythranthe (Spach) Greene)
Molecular studies by Beardsly & Olmstead (2002) had already shown that Mimulus in its traditional circumscription is not monophyletic. Barker & al. (2012) wrote a taxonomic conspectus of the entire family that is in accordance with phylogenetic data. Mimulus is accepted in a narrowed circumscription and only counts seven species from both the Old and New World, one of which has been recorded in Belgium (Mimulus ringens L.). It is cultivated as an ornamental in Europe (see Silverside 2000, Jäger & al. 2008) and has also been recorded in the British Isles as an alien (Clement & Foster 1994). All representatives of Mimulus s.l. that have been recorded as aliens in Belgium belong with Erythranthe, a genus of 111 species. Most are native in the New World (mostly North America and Mexico), while some occur in Asia. Several species are popular ornamentals and widely cultivated. Extensive accounts for the genus in cultivation (evidently as “Mimulus”) are provided by Silverside (2000) and Jäger & al. (2008). As a result of hybridization and polyploidization species boundaries in some of these cultivated species are much blurred now (especially in Erythranthe guttata and E. lutea and other members from section Simiola (Greene) G.L. Nesom et N.S. Fraga). Interesting accounts that emphasize on these species and their hybrids are provided by Silverside (1998), Silverside (2000), Stace (2010), etc. However, in practice separation of these (notho-) taxa seems exceedingly difficult and additional studies are needed in order to assess the exact identity of Belgian populations. Therefore, at least for the time being, only species are accepted in this account, no hybrids (although at least one, Mimulus xrobertsii Silverside, has been reliably recorded). Moreover, yet another new allopolyploid species (Mimulus peregrinus Vallejo-Marín) was recently described from the British Isles (Vallejo-Marín 2012).
The usage of the generic name Erythranthe is not uncontested. For a discussion see Lowry & al. (2019) and Nesom & al. (2019).
1 Calyx teeth subequal. Entire plant glandular hairy. Corolla 10-25 mm long === Erythranthe moschata
Calyx teeth distinctly unequal, the upper tooth much longer than the lower 4. Plant glabrous in lower half (but often hairy in upper part with a mixture of glandular and eglandular hairs). Corolla 25-50 mm long === 2
2 Ground colour of corolla orange === E. cuprea (incl. hybrids)
Ground colour of corolla yellow == 3
3 Small simple (eglandular) hairs present in inflorescence and on calyx keels (but these sometimes hidden by dense glandular hairs!). Throat of corolla more or less closed by two boss-like swellings on lower lip. Corolla lobes unspotted (but often with red spots in throat). Fruiting stalk about equaling calyx, or slightly longer === E. guttata (incl. hybrids)
Small simple (eglandular) hairs absent in inflorescence and on calyx keels. Throat of corolla more or less open. Corolla with central lower lobe spotted (usually with a single blotch). Fruiting stalk 2-5x as long as calyx === E. lutea (incl. hybrids)
Literature:
Barker W.R., Nesom G.L., Beardsley P.M. & Fraga N.S. (2012) A taxonomic conspectus of Phrymaceae: A narrowed circumscription for Mimulus, new and resurrected genera, and new names and combinations. Phytoneuron 2012-39: 1-60. [available online at: http://www.phytoneuron.net/PhytoN-Phrymaceae.pdf]
Beardsley P.M. & Olmstead R.G. (2002) Redefining Phrymaceae: the placement of Mimulus, tribe Mimuleae, and Phryma. Am. J. Bot. 89(7): 1093-1102.
Beardsley P.M., Schoenig S.E., Whittall J.B. & Olmstead R.G. (2004) Patterns of evolution in western North American Mimulus (Phrymaceae). Am. J. Bot. 91(3): 474-489.
Clement E.J. & Foster M.C. (1994) Alien plants of the British Isles. BSBI, London: XVIII + 590 p.
Grant A.L. (1924) A monograph of the genus Mimulus. Annals of the Missouri Botanical Garden 11: 99-389.
Hadfield M. (1967) The genus Mimulus. Gard. Chron., Ser. 3 162(14): 22.
Hiesey W.M., Nobs M.A. & Björkman O. (1971) Experimental studies on the nature of species: 5. Biosytematics, genetics and physiological ecology of the Erythranthe section of Mimulus. Washington D.C., Carnegie Inst.: VI + 213 p.
Jäger E.J., Ebel F., Hanelt P. & Müller G. (eds.) (2008) Rothmaler Band 5. Exkursionsflora von Deutschland. Krautige Zier- und Nutzpflanzen. Springer Verlag, Berlin: 880 p.
Kern J. & Reichgelt Th. (1950) Over enige kritische planten van onze flora. Nederl. Kruidk. Arch. 57: 244-261.
Lowry D.B. & al. (2019) The case for the continued use of the genus name Mimulus for all monkeyflowers. Taxon 68(4): 617-623.
McArthur E.D. (1974) The cytotaxonomy of naturalized British Mimulus. Watsonia 10: 155-158.
Nesom G.L. (2012a) Taxonomy of Erythranthe Sect. Simiola (Phrymaceae) in the USA and Mexico. Phytoneuron 2012-40: 1-123. [available online at: http://www.phytoneuron.net/PhytoN-sectSimiola.pdf
Nesom G.L. (2012b) Taxonomy of Erythranthe Sect. Mimulosma (Phrymaceae). Phytoneuron 2012-41: 1-36. [available online at: http://www.phytoneuron.net/PhytoN-sectMimulosma.pdf]
Nesom G.L. & al. (2019) Response to “The case for the continued use of the genus name Mimulus for all monkeyflowers”. Taxon 68(4): 624-627. [available online at: http://www.mimulustaxonomy.net/055TaxonResponse.pdf]
Piękoś H. (1972) Rodzaj Mimulus L. w. Polsce. (The genus Mimulus L. in Poland). Fragm. Florist. Geobot. 18: 343-351.
Roberts R.H. (1964) Mimulus hybrids in Britain. Watsonia 6: 70-75.
Silverside A.J. (1994) Mimulus: 180 years of confusion. In: Perry A.R. & Ellis R.G. (eds.), The common ground of wild and cultivated plants: introductions, invasions, control and conservation. Cardiff: National Museum of Wales: 59-64.
Silverside A.J. (1998) Mimulus section Simiolus. In: Rich T.C.G. & Jermy A.C. (eds.), Plant crib: 258-260. BSBI, London. [available online at: http://www.bsbi.org.uk/Mimulus_Plant_Crib_1998_AJS.pdf]
Silverside A.J. (2000) Mimulus. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: 275-280.
Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.
Vallejo-Marín M. (2012) Mimulus peregrinus (Phrymaceae): A new British allopolyploid species. PhytoKeys 14: 1-14. [available online at: http://www.pensoft.net/J_FILES/3/articles/3305/3305-G-3-layout.pdf]
Vickery R.K. (1966) Spciation and isolation in section Simiolus of the genus Mimulus. Taxon 15: 55-63.
Vickery R.K. (1973) Crossing barriers in the yellow monkey flowers of the genus Mimulus, Scrophulariaceae. In: Bogart R. (ed.), Genetics Lectures 3: 33-82.
Vickery R.K. (1995) Speciation in Mimulus, or, can a simple flower color mutant lead to species divergence? Great Basin Nat. 55(2): 177-180.
Vickery R.K., Crook K.W., Lindsay D.W., Mia M.M. & Tai W. (1968) Chromosome counts in section Simiolus of the genus Mimulus (Scorphulariaceae), 7. New numbers for M. guttatus, M. cupreus and M. tilingi. Madroño 19: 211-218.
Vickery R.K. & Wullstein B.M. (1987) Comparison of six approaches to the classification of Mimulus sect. Erythranthe (Scrophulariaceae). Syst. Bot. 12(3): 339-364.
Von Bohlen C. (1995) El género Mimulus L. (Scrophulariaceae) en Chile. Gayana Bot. 52: 7-28.