Eryngium L.
Eryngium is a genus of ca. 250 species, mostly native in temperate and tropical America, Eurasia and North Africa (e.g. Wörz 2005). Two species are rare and decreasing natives in Belgium, Eryngium campestre L. and E. maritimum L. (Lambinon & Verloove 2012). It is by far the largest and taxonomically most complex genus of the family. Its monophyly was confirmed by molecular data (Calviño & al. 2008).
Numerous species of Eryngium are particularly decorative and are grown for ornament (e.g. Knees & Sinclair 1997, Jäger & al. 2008). Others are also used medicinally.
The five species in the key below are readily distinguished in general habit but diagnostic characteristics are not easily described in a dichotomous key.
1 Basal leaves pinnate or pinnately lobed almost to base. Heads green to brownish (native) === Eryngium campestre
Basal leaves entire or lobed at most ½ to midrib. Heads bluish or greyish === 2
2 Heads few (usually 3-9) === 3
Heads numerous === 4
3 Bracts 6-10, leaf-like, broadly lanceolate. Basal leaves not lobed. Heads 30-70 mm long === Eryngium giganteum
Bracts 10-15, linear-lanceolate. Basal leaves 3-parted. Heads 15-25 mm long === E. bourgatii
4 Bracts usually ovate to obovate, leaf-like. Basal leaves lobed almost ½ to midrib. Heads ca. 20-25 mm across (native) === E. maritimum
Bracts linear. Basal leaves serrate but not lobed. Heads ca. 10-15 mm across === E. planum
Literature:
Calviño C.I., Martínez S.G. & Downie S.R. (2008) The evolutionary history of Eryngium (Apiaceae, Saniculoideae): Rapid radiations, long distance dispersals, and hybridizations. Molecular Phylogenetics and Evolution 46: 1129-1150. [available online at: http://www.life.illinois.edu/downie/MPE_Eryngium.pdf]
Fröberg L. (2010) Eryngium. In: Jonsell B. & Karlsson T. (eds.), Flora Nordica, vol. 6. The Swedish Museum of Natural History, Stockholm: 218-221.
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.
Knees S.G. & Sinclair N.J. (1997) Eryngium. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 5. Cambridge University Press, Cambridge: 396-399.
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.
Molinas M.-L., Perdigo M.-T. (1984) Iconografía dels fruits d'algunes especies del genere eryngium de l'Europa Oriental i orient proper. Folia Bot. Misc. 4: 19-28.
Nieto Feliner G. (2000) Taxonomic notes on Eryngium (Apiaceae) from the West Mediterranean. An. Jard. Bot. Madrid 58(2): 367-371.
Perdigo M.T. & Molinas M.L. (1986) Iconografía dels fruits d'algunes especies del genere Eryngium: 2. (Iconography of the fruits of seven species of Eryngium from Spain and Africa.). Folia Bot. Misc. 5: 9-14.
Reduron J.-P. (2007) Ombellifères de France. Vol. 3. Bull. Soc. Bot. Centre-Ouest 28: 1-1726.
Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.
Wörz A. (1999) A taxonomic index of the species of Eryngium L. (Apiaceae: Saniculoideae). Stuttgarter Beitr. Naturk., ser. A 596: 1-48.
Wörz A. (2005) A new subgeneric classification of the genus Eryngium L. (Apiaceae, Saniculoideae). Bot. Jahrb. 126: 253-259.
Wörz A. (2006) Systematics and distribution patterns of the Balkan species of Eryngium
(Apiaceae, Saniculideae). Phytol. Balcan. 12(2): 221-230. [available online at: http://www.bio.bas.bg/~phytolbalcan/PDF/12_2/12_2_10_Worz.pdf]
Wörz A. (2011) Revision of Eryngium L. (Apiaceae-Saniculoideae): General part and Palaearctic species. Bibliotheca Botanica 159: 498 p.
Wolff H. (1913) Eryngium. In: Engler A. (ed.), Das Pflanzenreich 61 (IV/228). Engelmann, Leipzig: 106-271.