Dryopteris erythrosora (Eaton) Kuntze (China, Japan) – A very rare escape from cultivation, known from only four localities. First discovered in woodland in Brugge in 2015 (a single individual). In the same year also recorded in woodland near Antwerpen (Hoboken). In 2017 observed on a woody talus slope in Genk and in a basement in Gent.
Dryopteris erythrosora is unmistakable due to its coppery-pink young fronds and indusia. It has been reported as a garden escape in the British Isles (Edgington 2003) and in the Netherlands (www.waarneming.nl).
Dryopteris erythrosora is part of a species complex that includes at least 17 species (Lin & Iwatsuki 2010). At least one of these, D. hondoensis Koidz., is also grown as an ornamental (Joe Hoshizaki & Wilson 1999).
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Selected references
Edgington J.A. (2003) Ferns of the metropolis – a status report. Lond. Nat. 82: 59-73.
Hori K., Watano Y. & Murakami N. (2017) Hybrid Origin of the Apogamous Fern Dryopteris hondoensis (Dryopteridaceae). Acta Phytotaxonomica Geobotanica 67(3): 133-146. [available online at: https://www.researchgate.net/publication/311290013_Hybrid_Origin_of_the_...
Joe Hoshizaki B. & Wilson K.A. (1999) The cultivated species of the fern genus Dryopteris in the United States. American Fern Journal 89: 1-98. [available online at: http://www.biodiversitylibrary.org/item/100122#page/1/mode/1up]
Lin S.J. & Iwatsuki K. (2010) A new sexual diploid of Dryopteris erythrosora complex (Dryopteridaceae) from Oki Islands, Japan. Bull. Fac. Life Env. Sci. Shimane Univ. 15: 11-13. [available online at: http://www.lib.shimane-u.ac.jp/kiyo/d004/0015/003.pdf]
Nakaike T. & Yamamoto A. (1984) Observations on the Dryopteris erythrosora group in Oshima isl., Tokyo. Bull. Nation. Sci. Mus., B (Tokyo) 10(1): 51-62.
Nakaike T., Yamamoto A. & Maki M. (1984) A study in distribution, habitat, character variation of Dryopteris erythrosora (Aspidiaceae) of the Izu Peninsula. Bull. Nation. Sci. Mus., B (Tokyo) 10(4): 191-202.
Umstead H. & Diggs J.T. (2018) An Ornamental Plant Found Spreading Aggressively: Potential Invasiveness of Dryopteris erythrosora (Dryopteridaceae) in North America. American Fern Journal 108(4): 176-179.
Yamamoto A. & Nakaike T. (1984) Observations on the Dryopteris erythrosora complex (Aspidiaceae) Hachioji, Tokyo. Bull. Nation. Sci. Mus., B (Tokyo) 10(2): 107-114.