Lobelia erinus L. (E and S-Afr.) – An increasing escape from cultivation but probably always ephemeral up to present. First collected in Stabroek in 1925 (possibly neglected before). Subsequently recorded in rather numerous and very widely scattered locations, mostly on dumps or in urban areas. Lobelia erinus usually grows in dry, sun-exposed habitats: foot of walls, pavement, gravelly soils,… In such places possibly persisting for some years but not really becoming naturalised (yet).
Lobelia erinus is a very popular and variable ornamental species. Compact forms (f. compacta) are used for bedding while trailing forms (f. pendula) prevail in hanging baskets. Both forms escape. Some plants are possibly hybrids involving Lobelia valida L. Bolus (see Jäger & al. 2008). In its area of origin Lobelia erinus is a perennial but in western Europe it is grown as an annual.
Flower stalks (pedicels) are said to be 1-2 cm long by Ayers (2000) but they are mostly much longer.
Literature
Ayers T.J. (2000) Lobelia and Pratia. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: resp. 499-501 and 496-498.
Jäger E.J., Ebel F., Hanelt P. & Müller G. (eds.) (2008) Rothmaler Band 5. Exkursionsflora von Deutschland. Krautige Zier- und Nutzpflanzen. Springer Verlag, Berlin: 880 p.