A. Carlström, New taxa and notes from the SE Aegean area and SW Turkey in Willdenowia 16. 1986L. Zeltner, Recherches de biosystématique sur les genres Blackstonia Huds. et Centaurium Hill in Bull. Soc. Neuchateloise Sci. Nat. 93. 1970L. Zeltner, Etude cytotaxonomique et cytogéographique de Centaurium pulchellum (Swartz) Druce, sensu lato in Bot. Helv. 95. 1985L. Zeltner, Contribution à l'étude cytogéographique des genres Blackstonia Huds. et Centaurium Hill (Gentianaceae) en Turquie, à Rhodes et à Chypre in Bull. Soc. Neuchateloise Sci. Nat. 114. 1991R. D. Meikle, Flora of Cyprus 2. 1985
This key is to be understood as provisional and for testing purposes. Further studies are needed to clarify if morphology correlates with caryological differentiation. The key is based on descriptions in the cited publications.
1Corolla yellow; corolla tube 15-20 mm long; capsule 12-15 mm long
1'Corolla pink, rarely white; corolla tube 6-16 mm long; capsule 7-12 mm long
2Corolla lobes longer than 5 mm
2'Corolla lobes shorter than 5 mm
3Leaves commonly forming a persistent rosette; corolla lobes 8-12 mm long
3'Without rosette or leaves forming a loose pseudo-rosette generally withering before anthesis; corolla lobes 5-8.5 mm long
4Corolla tube 6-11 mm long; corolla lobes 5-8 mm long; plants branched from near the base
4'Corolla tube 12-16 mm long; corolla lobes 7-8.5 mm long; plants branched in the upper half only
5Plants often branched from near the base; inflorescence lax, open
5'Plants often branched in the upper half only; inflorescence repeatedly branched, fastigiate
6Flowers 2-90; corolla lobes dark pink; corolla tube not constricted below the limb; often with pseudo-rosette
6'Flowers 20-180; corolla lobes pale pink; corolla tube constricted below the limb; forming no rosette