Petrorhagia (Seringe) Link
(incl. Kohlrauschia Kunth)
The generic limits of Petrorhagia are unclear and since long debated. Some authors raise section Kohlrauschia to generic rank (e.g. Bittrich 1993). Mabberley (2008) on the one hand accepts Kohlrauschia as a separate genus (accomodating five closely related species, including K. prolifera (L.) Kunth, syn.: Petrorhagia prolifera (L.) P.W. Ball et Heywood) but, on the other hand, also accepts P. prolifera under Petrorhagia. Pending future molecular phylogenetic research Petrorhagia is here tentatively treated in a broad sense as to include Kohlrauschia. As such, it counts ca. 33 species mainly distributed in the Mediterranean area, Macaronesia and parts of Asia. One species, Petrorhagia prolifera, is native in Belgium (Lambinon & Verloove 2012). However, it is also frequently introduced in port areas, along road verges, etc. and many of its populations are obviously non-native. Petrorhagia prolifera belongs to a complex of few, very closely related species (section Kohlrauschia) that is poorly understood in Belgium. British populations of presumably native ‘Petrorhagia prolifera’ eventually turned out to belong to three distinct species of which only P. nanteuilii proved to be native (Clement 2005). All species are superficially very similar but readily distinguished on seed and leaf sheath characters.
1 Perennial. Epicalyx segments about ½ as long as calyx. Flowers solitary or in lax cymes, pedicellate. Petals 4-10 mm long === Petrorhagia saxifraga
Annual. Epicalyx segments about as long as and largely obscuring calyx. Flowers sessile in a capitate inflorescence (but usually only one flowering at the time). Petals usually ca. 10-15 mm long === 2
2 Seeds tuberculate. Leaf sheaths longer than wide, (2-)3-4 mm long. Petals emarginate to bifid at apex, usually with 1-3 veins darkly coloured at base === P. nanteuilii
Seeds finely reticulate-granulate. Leaf sheaths ca. as long as wide, usually 1-2 mm long. Petals entire to emarginate at apex, veins not darkly coloured at base (native) === P. prolifera
Literature:
Akeroyd J.R. & Beckett G. (1995) Petrorhagia prolifera (L.) PW Ball and Heywood (Caryophyllaceae), an overlooked native species in eastern England. Watsonia 20(4): 405-407.
Ball P.W. & Akeroyd J.R. (1993) Petrorhagia. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 1. (2nd ed.). Cambridge University Press, Cambridge: 224-227.
Ball P.W. & Heywood V.H. (1962) The taxonomic separation of the cytological races of Kohlrauschia prolifera (L.) Kunth sensu lato. Watsonia 5(3): 113-116.
Ball P.W. & Heywood V.H. (1964) A revision of the genus Petrorhagia. Bull. Brit. Mus. (Nat. Hist.), Bot. 3: 121-172.
Bittrich V. (1993) Caryophyllaceae. In: Kubitzki K. et al. (eds.) The Families and Genera of Vascular Plants, vol. 2. Berlin, etc.: 206-236.
Clement E.J. (2005) Petrorhagia dubia established in S. Hants (V.C. 11). BSBI News 100: 46.
Lambinon J. & Verloove F. (avec coll. Delvosalle L., Toussaint B., Geerinck D., Hoste I., Van Rossum F., Cornier B., Schumacker R., Vanderpoorten A. & Vannerom H.) (2012) Nouvelle Flore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des Régions voisines (Ptéridophytes et Spermatophytes). Sixième édition. Jardin botanique national de Belgique, Meise: CXXXIX + 1195 p.
Mabberley D.J. (2008) Mabberley’s plant-book (3th ed.). Cambridge University Press, Cambridge: XVIII + 1021 p.
Rabeler R.K. (1984) Notes on nomenclature within Petrorhagia (Caryophyllaceae). Taxon 33(4): 714-716.
Rabeler R.K. (1985) Petrorhagia (Caryophyllaceae) in North America. Sida 11: 6-44.
Rabeler R.K. & Hartman R.L. (2005) Petrorhagia. In: Flora of North America Editorial Committee (eds.), Flora of North America, vol. 5. Oxford University Press, New York-Oxford: 162-165.
Romo A.M. (1990) Petrorhagia. In: Castroviejo S. & al. (eds.), Flora Iberica, vol. 2. Real Jardín Botánico, Madrid: 420-426.
Thomas S.M. (1983) A taxonomic clarification of Petrorhagia section Kohlrauschia (Caryophyllaceae). Bot. J. Linn. Soc. 87(1): 55-75.
Thomas SM. & Murray B.G. (1983) Chromosome studies in species and hybrids of Petrorhagia sect. Kohlrauschia (Caryophyllaceae). Pl. Syst. Evol. 141(3-4): 243-255.
Thomas SM. & Murray B.G. (1981) Breeding systems and hybridization in Petrorhagia sect. Kohlrauschia (Caryophyllaceae). Pl. Syst. Evol. 139(1-2): 77-94.