Mazus reptans N.E. Brown (syn.: M. miquelii) (Cult.) – An exceptional alien. Discovered on peaty soil on a pond margin in a garden in Olen in 2015. The species spontaneously occurred on peat imported few years earlier (in 2011) from a heath in Lower Saxony in Germany (while it is unknown from that country).
The taxonomy of this species long remained unresolved. The plants from Olen have leaves all rather similar in size, with acute teeth in their upper parts and the inflorescence is shortly stalked. These characters are typical of Mazus reptans, a species only known in cultivation. It was always said to be closely related to the eastern Asian M. miquelii Makino (Mill 2000). Pringle (2018), however, demonstrated that naturalized plants named M. reptans in North America do not differ from the type of M. miquelii. If both are indeed conspecific, then the latter name should be applied for nomenclatural reasons.
Mazus reptans is increasingly cultivated as an ornamental. It has started escaping from cultivation, for instance in parts of North America (Rabeler & Freeman 2013) and Europe (Banfi & Galasso 2010, Bertolli & Prosser 2014).
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Selected literature:
Banfi E. & Galasso G. (eds.) (2010) La flora esotica lombarda. Museo di Storia Naturale di Milano, Milano: 274 pp. + CD-ROM.
Bertolli A. & Prosser F. (2014) Segnalazioni Floristiche Tridentine. IX. Ann. Mus. civ. Rovereto Sez.: Arch., St., Sc. nat. 29 (2013): 131-174. [available online at: http://www.museocivico.rovereto.tn.it/UploadDocs/6340_art06_prosser_bertolli.pdf]
Kimata M. (1978) Comparative studies on the reproductive systems of Mazus japonicus and M. miquelii (Scrophulariaceae). Pl. Syst. Evol. 129(4): 243-253.
Mill R.R. (2000) Mazus. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: 280-282.
Pringle J.S. (2018) The Identification, Nomenclature, and Naturalized Distribution of Mazus miquelii (Mazaceae) in North America. Castanea 83(2): 216-223.
Rabeler R.K. & Freeman C.C. (2013) Mazaceae. Flora of North America, Provisional Publication. Flora of North America Association. February 15, 2013. [available online at: http://floranorthamerica.org/files/Mazaceae03f%20SI%20CH%20for%20web.pdf]