Nemophila menziesii Hook. et Arnott (western USA) – A rare and ephemeral alien, known since the end of the 19th century (Verloove 2006). In recent years documented for instance from Hérinnes, Petegem-aan-de-Schelde and Turnhout. All records are obviously associated with wildflower seed mixtures, either as relics or as impurities in such or other mixtures.
Nemophila menziesii is a variable species and several infraspecific taxa have been described. A form with almost undivided leaves (var. integrifolia Parish) was recorded once in 1895 (Verloove 2006). The plants usually seen, however, have distinctly lobed leaves and flowers with a clear (unspotted) white center; they belong to var. menziesii. (syn.: Nemophila insignis Benth.). Var. atomaria (Fisch. et C.A. Mey.) H.P. Chandler is also cultivated and it is distinguished in having flowers that are black-spotted throughout. It may also be found as an alien.
Selected references:
Barr C.M. (2004) Hybridization and regional sex ratios in Nemophila menziesii. Journal of Evolutionary Biology 17: 786-794.
Chandler H.P. (1907) Notes on two California Nemophilas. Botanical Gazette 44: 381–382. [available online at: https://www.biodiversitylibrary.org/item/90333#page/485/mode/1up]
Cruden R.W. (1972) Information on chemistry and pollination biology relevant to the systematics of Nemophila menziesii (Hydrophyllaceae). Madroño 21(8): 505-515. [available online at: https://www.biodiversitylibrary.org/item/185322#page/541/mode/1up]
Cruden R.W. (1972) Pollination biology of Nemophila menziesii (Hydrophyllaceae) with comments on the evolution of oligolectic bees. Evolution 26(3): 373-389. [available online at: http://onlinelibrary.wiley.com/doi/10.1111/j.1558-5646.1972.tb01943.x/epdf]
Ganders F.R. (1978) The genetics and evolution of gynodioecy in Nemophila menziesii (Hydrophyllaceae). Canad. J. Bot. 56(12): 1400-1408.
Verloove F. (2006) Catalogue of neophytes in Belgium (1800-2005). Scripta Botanica Belgica 39: 89 p. [available online at: http://alienplantsbelgium.be/sites/alienplantsbelgium.be/files/tabel_2.pdf]