Gilia achilleifolia Benth. (California) – A rare and ephemeral alien. Most if not all records are clearly associated with wildflower seed mixtures. First documented in 1954 from a railway siding in Kessel-Lo. In recent years more often seen, for instance in Geel, Schaarbeek, Sint-Niklaas, etc.
Typical plants are easily distinguished from G. capitata in having relatively few-flowered inflorescences (with only some flowers open at the same time) and short stamens that barely reach the tip of the corolla lobes. Some plants, however, are difficult to positively assign to one of both species. G. achilleifolia has been suggested to be of hybrid origin with one of its putative parents being G. capitata s.l. However, molecular and morphological analyses of G. achilleifolia and related species have failed to confirm this hypothesis (Morrell & Rieseberg 1998).
Both Gilia achilleifolia and G. capitata are frequent components and wildflower seed mixtures, also in other countries, e.g. in the British Isles (Wurzell 1995).
Morrell P.L. & Rieseberg L.H. (1998) Molecular tests of the proposed diploid hybrid origin of Gilia achilleifolia (Polemoniaceae). Amer. J. Bot. 85(10): 1439-1453. [available online at: http://www.amjbot.org/content/85/10/1439.full]
Schoen D.J. (1977) Morphological, phenological and pollen-distribution evidence of autogamy and xenogamy in Gilia achilleifolia (Polemoniaceae). Syst. Bot. 2(4): 280–286.
Schoen D.J. (1982) The breeding system of Gilia achilleifolia: variation in floral characteristics and outcrossing rate. Evolution 36(2): 352-360. [available online at: http://download.xuebalib.com/xuebalib.com.37046.pdf]
Wurzell B.S. (1995) Two Gilia species in north-east London. B.S.B.I. News 70: 32-33. [available online at: http://archive.bsbi.org.uk/BSBINews70.pdf]