Anchusa azurea Mill. (syn.: A. italica Retz.) (Medit., Macaronesia) – A rare and nearly always ephemeral alien (sometimes persisting for some time, for instance between Ottignies and Rixensart between 1877 and 1880). Already recorded (without further details) before 1850. Most records are from the 2nd half of the 19th and the first half of the 20th century. Much decreasing in the past decades. Since 1950 only known from very scattered locations: Brussel (1950), Lamorteau (1950) and port of Antwerpen (2000). Anchusa azurea is most often seen on stony and sunny substrates: railway banks, coal mine heaps, gravel pits, waste land,… Many records are obviously associated with grain importation and very few (if any) seem to represent escapes from cultivation.
Several herbarium collections were confused with Anchusa officinalis (many records of A. azurea turned out to belong to the latter). In Anchusa azurea nutlets are much larger, the calyx more deeply divided and the corollas are deep blue.
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Selected literature:
Akcin T.A., Ulu S. & Akcin A. (2010) Morphological, anatomical and numerical studies on some Anchusa L. (Boraginaceae) taxa from Turkey. Pak. J. Bot. 42(4): 2231-2247. [available online at: http://www.pakbs.org/pjbot/PDFs/42(4)/PJB42(4)2231.pdf]
Lemke D.E. & Wesby V. (1989) Anchusa azurea (Boraginaceae) new to Texas. Sida 13: 516.