Maianthemum dilatatum (A.W. Wood) A. Nelson & J.F. Macbride) (syn.: M. kamtschaticum (Chamisso) Nakai) (E As., western N Am.) – An exceptional alien, probably a garden throw-out. Discovered in woodland in Peer in 2013.
This species and native Maianthemum bifolium are much alike and have been considered one variable species by some authors. In eastern Asia M. dilatatum is sympatric with M. bifolium and in Japan there occur intermediate forms which may have derived from hybridization between the two species. Such plants have been called M. intermedium Voroschilov in the Russian Far East (Chen & al. 2000). M. dilatatum is a larger plant with multi-flowered inflorescences and more appropriate for horticultural purposes. It may have been overlooked so far.
There are but few records of Maianthemum dilatatum as an escape in Europe, except perhaps from the British Isles where the species is known since the 1980’s and seems to spread locally (Clement & Foster 1994, Stace 2010).
Maianthemum dilatatum grows best in moist to wet environments, usually shady woods and riverside areas, and prefers acid, neutral and basic (alkaline) soils. In suitable habitats it is a fast colonizer (mainly clonal growth) and it may become invasive (Huxley 1992). If it would become more widespread, then introgression with native M. bifolium is not unlikely (see also above).
Some authors refer to this species as Maianthemum kamtschaticum (e.g. Leslie 1986, Stace 2010). The latter binomial, however, is a younger synonym.
Selected literature:
Chen S.C., Liang S.J., Xu J.M. & Tamura M.N. (2000) Liliaceae. In: Wu Z.Y. & Raven P.H. (eds.), Flora of China, vol. 24: 73-263. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis. [available online at: http://flora.huh.harvard.edu/china/mss/volume24/LILIACEAE.published.pdf]
Clement E.J. & Foster M.C. (1994) Alien plants of the British Isles. BSBI, London: XVIII + 590 p.
Huxley A. (1992) The New RHS Dictionary of Gardening. MacMillan Press.
Kawano S., Ihara M. & Suzuki M. (1968b) Biosystematic studies on Maianthemum (Liliaceae-Polygonateae [sic]). IV. Variation in gross morphology of M. kamtschaticum. Bot. Mag. (Tokyo) 81: 473-490.
Leslie A. (1986) Maianthemum. In: Walters S.M. & al. (eds.), The European Garden Flora, vol. 1. Cambridge University Press, Cambridge: 253.
Lezberg A.L., Halpern C.B. & Antos J.A. (2001) Clonal development of Maianthemum dilatatum in forests of differing age and structure. Canad. J. Bot. 79(9): 1028-1038. [available online at: https://www.researchgate.net/publication/254352072_Clonal_development_of_Maianthemum_dilatatum_in_forests_of_differing_age_and_structure]
Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.
Utech F.H. & Kawano S. (1976) Biosystematic studies on Maianthemum (Liliaceae). VIII. Floral anatomy of M. dilatatum, M. bifolium, M. canadense. Bot. Mag. (Tokyo) 89: 145-157.
Wilson A. (2004) Characterization of clonal structure and mating patterns in Maianthemum dilatatum. MSc Thesis University of British Columbia [available online at: http://elk.library.ubc.ca/bitstream/handle/2429/15174/ubc_2004-0135.pdf?sequence=1]
Wilson A.S.G., van der Kamp B.J. & Ritland C. (2005) Spatial genetic and clonal structure in Maianthemum dilatatum as defined by AFLP markers. Revue canadienne de botanique 83(9): 1126-1132.