Dianthus L.
Dianthus is, in its traditional sense, a large genus of ca. 320 species, mainly distributed in Eurasia (few species in America and Africa) (Mabberley 2008). Four species are native in Belgium: Dianthus armeria L., D. carthusianorum L., D. deltoides L. and D. gratianopolitanus Vill. (Lambinon & Verloove 2012). These species are also cultivated as ornamentals and sometimes occur in wild flower seed mixtures or as escapes from cultivation outside their natural distribution range. The genus Dianthus is very popular among horticulturists (Carnations, Pinks). As a result of hybridization and selection most garden plants are no longer assignable to any particular species (Hamilton & Walters 1989).
Recent molecular studies by Greenberg & Donoghue (2011) demonstrated Dianthus to be not monophyletic if Velezia L. were recognized as a separate genus. A recent study of the European radiation of Dianthus also supported the inclusion of Velezia within this genus (e.g. Harbaugh & al. 2010).
1 Inflorescence capitate, always surrounded by conspicuous involucral bracts. Flowers several per head, (sub-) sessile === 2
Inflorescence not capitate, involucral bracts absent or inconspicuous. Flowers solitary or in cymes, pedicellate === 5
2 Annual or biennial (without non-flowering shoots), 10-40 cm tall. Plant pubescent, at least in inflorescence (native) === Dianthus armeria
Perennial, usually much taller and with non-flowering shoots. Plant (sub-) glabrous === 3
3 Leaves lanceolate-elliptic, 10-25 mm wide. Leaf sheath less than 5 mm long (less than 3x diameter of stem). Involucral bracts greenish, herbaceous === Dianthus barbatus
Leaves linear, at most 8 mm wide. Leaf sheath 10-20 mm long (more than 3x diameter of stem). Involucral bracts brownish, coriaceous === 4
4 Very robust, up to 100 cm tall. Leaves to 8 mm wide. Inflorescence many-flowered (usually much more than 4 flowers per head). Epicalyx segments gradually tapered at apex === D. giganteus
Less robust, up to 60 cm tall. Leaves to 5 mm wide, usually much less. Inflorescence few-flowered (usually with 3-4 flowers per head). Epicalyx segments cuspidate at apex (native) === D. carthusianorum
5 Petal limb deeply laciniate, divided +/- half way to base or more === D. plumarius
Petal limb entire, dentate or shallowly laciniate === 6
6 Stem finely pubescent-scabrous. Flowers scentless (native) === D. deltoides
Stem glabrous. Flowers scented === 7
7 Erect, tufted perennial, to 60 cm tall. Flowers > 30 mm across. Calyx 25-30 mm long. Petals not bearded === D. caryophyllus
Dwarf, +/- mat-forming perennial, to 20 cm tall. Flowers < 30 mm across. Calyx 10-20 mm long. Petals bearded or not === 8
8 Calyx ca. 10 mm long. Petals not bearded === D. subacaulis
Calyx 13-20 mm long. Petals bearded (native) === D. gratianopolitanus
Additional alien: Dianthus superbus L. (C and N-Eur., C-As., garden escape).
Literature:
Greenberg A.K. & Donoghue M.J. (2011) Molecular systematics and character evolution in Caryophyllaceae. Taxon 60(6): 1637-1652. [available online at: http://donoghuelab.yale.edu/sites/alienplantsbelgium.bedefault/files/208_greenberg_taxon11_0.pdf]
Hamilton R.F.L. & Walters S.M. (1989) Dianthus. In: Walters S.M. & al. (eds.), The European Garden Flora, vol. 3. Cambridge University Press, Cambridge: 185-191.
Harbaugh D.T., Nepokroeff M., Rabeler R.K., McNeill J., Zimmer E.A. & Wagner W.L. (2010) A new lineage-based tribal classification of the family Caryophyllaceae. Int. J. Pl. Sci. 171: 185-198. [available online at: http://si-pddr.si.edu/bitstream/10088/9723/1/bot_Harbaugh_et_al_2010-Caryophyllaceae.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.
Kurtto A. (2001) Caryophyllaceae. In: Jonsell B. (ed.), Flora Nordica, vol. 2. The Bergius Foundation, Stockholm: 83-216.
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.
McDonald N. (1996) Pinks and gilliflowers: an introduction to Dianthus. Rock Gard. Quart. 54(4): 266-286.
Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.
Tutin T.G. & Walters S.M. (1993) Dianthus. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 1 (2nd ed.). Cambridge University Press, Cambridge: 227-246.
Williams F.N. (1893) Monograph of the genus Dianthus. J. Linn. Soc. (Bot.) 29: 346-378.