Trachystemon orientalis (L.) G. Don f. (syn.: Borago orientalis L., Psilostemon orientalis (L.) DC.) (Bulgaria, Turkey) – A very rare, locally naturalized relic of cultivation or escape. Known at least since the 1950’s from the Sterrebos in Roeselare (Lawalrée 1956). Here Trachystemon orientalis was long confined to its initial area of introduction and was considered merely persistent by Verloove (2002). However, in the past years it has sudenly spread and now occurs in at least two additional populations where it was never planted. It is obviously naturalized recently at this location. Furthermore, observed in 2008 as escaping from a plantation in the Vrijbroekpark in Mechelen. Other recent records, all from Flanders, are available from Korbeek-Lo and Loppem (see: http://waarnemingen.be/soort/view/136817 for an up-to-date overview). In all cases Trachystemon orientalis grows in shady, dampish woodlands.
In recent years it is introduced in Germany as a minor crop plant by Turkish immigrants (Gladis & Pistrick 2011).
Trachystemon orientalis superficially looks like Borago but it is a rhizomatous perennial and its calyx is only divided for half its length.
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Selected literature:
Akçin Ö.E., Kandemir N. & Akçin Y. (2004) A morphological and anatomical study on a medicinal and edible plant Trachystemon orientalis (L. ) G. Don (Boraginaceae) in the Black Sea region. Turk. J. Bot. 28: 435-442. [available online at: http://journals.tubitak.gov.tr/botany/issues/bot-04-28-4/bot-28-4-7-0212-2.pdf]
Gladis T. & Pistrick K. (2011) Chaerophyllum byzantinum Boiss. and Trachystemon orientalis (L.) G. Don—recently introduced from Turkish wild flora as new crop species among other interesting findings from immigrant gardens in western Germany. Genetic Resources and Crop Evolution 58(1): 165-174.
Goos U., Hentsch M., Keil P. & Loos G.H. (2002) Zwei Vorkommen von Trachystemon orientalis (L.) G. Don fil. (Boraginaceae) im Ruhrgebiet. Flor. Rundbr. 36(1-2): 63-68.
Kendrick F.M. (1978) Botany, 1978. Trans. Woolhope Naturalists' Field Club 42: 284.
Lawalrée A. (1956) Phanérogames adventices ou naturalisées en Belgique. Bull. Soc. Roy. Bot. Belg. 88: 25-28.
Radkowitsch A. (2003) Cymbalaria pallida und Trachystemon orientalis: zwei bemerkenswerte Adventivarten im Naturraum Schwarzwald-Randplatten. Berichte der Botanischen Arbeitsgemeinschaft Südwestdeutschland 2: 117-119. [available online at: http://www.botanik-sw.de/BAS/media/texte/Bericht_2.pdf]
Verloove F. (2002) Ingeburgerde plantensoorten in Vlaanderen. Mededeling van het Instituut voor Natuurbehoud n° 20: 227 p.
Wallnöfer B., Strudl M. & Pokorny M. (2015) Über fremdländische Arten von Cephalaria (Dipsacaceae), Gilia (Polemoniaceae), Ornithopus (Fabaceae) und Trachystemon (Boraginaceae) in Österreich. Stapfia 103: 151-159. [available online at: http://www.zobodat.at/pdf/STAPFIA_0103_0151-0159.pdf]