1. Bistorta amplexicaulis (D. Don) Greene (syn.: Persicaria amplexicaulis (D. Don) Ronse Decraene, Polygonum amplexicaule D. Don) (Himalayas) – A very rare and ephemeral garden escape. First seen in wasteland in Brussel in 1966 (Lambinon 1995). Recently recorded in an increasing number of localities, for instance in woodland in Beernem in 2003 and on rough ground in Schepdaal and Neder-over-Heembeek in 2011.
Bistorta amplexicaulis is increasingly cultivated in recent times (especially in public greenery) and the number of new records will probably increase likewise.
Plants in cultivation and in the wild are nearly always ascribable to (Persicaria amplexicaulis) var. speciosa (J.D. Hook.) Akeroyd, characterized by its deep pinkish to reddish inflorescences (Akeroyd 2013). There are, however, numerous cultivars in the horticultural trade (Huisman & van der Linden 2018). Some of the cultivars moreover belong to hybrids of B. officinalis and B. amplexicaulis (idem).
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Selected literature:
Akeroyd J.R. (2013) New nomenclatural combinations in Persicaria (L.) Miller and a new hybrid in Rumex L. (Polygonaceae). Contribuţii Botanice 48: 15-21. [available online at: http://reviste.ubbcluj.ro/contributii_botanice/materiale/2013/Contrib_Bot_vol_48_pp_015-021.pdf]
Armitage J.D. (2013) New combinations in Persicaria amplexicaulis (D. Don) Ronse Decr. and the reinstatement of the cultivar name 'Arun Gem'. Hanburyana 7: 47-50.
Huisman N. & van der Linden M. (2018) Persicaria amplexicaulis. Sortimentsonderzoek en keuringsrapport. Dendroflora 54: 68-93.
Lambinon J. (1995) Notes taxonomiques, nomenclaturales et chorologiques relatives à la quatrième édition de la « Nouvelle Flore » de la Belgique et des régions voisines. 3. Données nouvelles sur des plantes adventices ou subspontanées en Belgique. Dumortiera 60: 1-36.
Yonekura K. & Ohashi H. (2002) Taxonomic studies of Bistorta (Polygonaceae) in the Himalayas and adjacent regions. II. Bistorta amplexicaulis (D. Don) Greene and its allies, with special reference to the ochreae and leaf sheaths of cauline leaves. Journ. Jap. Bot. 77(2): 61-81.