Phlox L.
Phlox is a genus with 69 almost exclusively North American species (Mabberley 2008). Numerous species are widely grown as garden ornamentals. Useful accounts for the genus in cultivation are provided by e.g. Brown (2000; 22 species) and Jäger & al. (2008). A few of these have been recorded as escapes in Belgium.
Phlox is taxonomically complex and hybridization may have severely affected relationships in this genus (Ferguson & Jansen 2002). A modern revision of the genus is therefore much needed, the latest monograph dating back to Wherry (1955).
1 Perennial with erect stems, without decumbent sterile shoots. Leaves lanceolate to ovate, 10-50 mm wide. Inflorescence a compound, multi-flowered panicle (with often more than 100 or several 100’s of flowers) === Phlox paniculata
Mat forming perennial with decumbent leafy sterile stems. Leaves linear to subulate. Inflorescence few-flowered (with 3-6 flowers) === P. subulata
Literature
Brown N. (2000) Phlox. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: 104-109.
Cooperrider T.S. (1986) The genus Phlox (Polemoniaceae) in Ohio. Castanea 51(2): 145-148.
Ferguson C.J. & Jansen R.K. (2002) A chloroplast DNA phylogeny of eastern Phlox (Polemoniaceae): implications of congruence and incongruence with the ITS phylogeny. American Journal of Botany 89(8): 1324-1335. [available online at: http://www.amjbot.org/content/89/8/1324.full]
Ferguson C.J., Kramer F. & Jansen R.K. (2000) Relationships of eastern North American Phlox (Polemoniaceae) based on ITS sequence data. Syst. Bot. 24(4): 616-631.
Grant V. (2001) Nomenclature of the main subdivisions of Phlox (Polemoniaceae). Lundellia 4: 25-29. [available online at: http://w3.biosci.utexas.edu/prc/pdfs/Grant02_Lundellia04.pdf]
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.
Mabberley D.J. (2008) Mabberley’s plant-book (3th ed.). Cambridge University Press, Cambridge: XVIII + 1021 p.
Turner B.L. (2003) Atlas of the Texas species of Phlox (Polemoniaceae). Phytologia 85(5): 309-326. [available online at: https://www.biodiversitylibrary.org/item/47137#page/5/mode/1up]
Wherry E.T. (1955) The genus Phlox. Morris Arboretum Monographs 3: 174 pp.
Additional alien: Phlox maculata L. (USA, garden escape).