The family Polemoniaceae counts about 20 genera and 400 species. All are native to America, Europe and northern Asia but none is native to Belgium. Its center of diversity is in western North America. Numerous species are grown as garden ornamentals (see e.g. Ingram 1959, Cullen & al. 2000, Jäger & al. 2008 for useful accounts for the family in cultivation) and several of these have been recorded as escapes in Belgium. In addition, a few species are weedy and some of these have been documented from Belgium as well.
The monophyly of Polemoniaceae was strongly supported by molecular studies (e.g. Johnson & al. 1999 and subsequent authors).
Useful additional information about the family is provided by Johnson (2009), online at: http://tolweb.org/Polemoniaceae/20812.
1 Leaves mostly opposite, entire === Phlox
At least upper leaves alternate, pinnate to bi-pinnate === 2
2 Leaves and bracts spinescent === Navarretia
Leaves and bracts not spinescent === 3
3 Slender annual. Leaves pinnate to bipinnate, with linear segments === Gilia
Perennial herbs. Leaves pinnate, with lanceolate segments === Polemonium
Cullen J. & al. (eds.) (2000) The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: 100-111.
Ingram J. (1959) Notes on the cultivated Polemoniaceae. 1. A key to the genera. Baileya 7: 80-86.
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.
Johnson L A., Soltis D.E. & Soltis P.S. (1999) Phylogenetic affinities of Polemoniaceae inferred from nuclear ribosomal 18S DNA sequences. Plant Syst. Evol. 214: 65-89.