Rhagadiolus

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Description

Annual herbs. Stem usually branched. Leaves dentate or pinnatisect, rarely subentire. Capitula homogamous, ligulate; phyllaries in 2 series, the outer very short, the inner longer, incurved at the apex, accrescent and patent in fruit, enveloping the outer achenes. Receptacle flat, naked. Flowers yellow. Achenes subulate or narrowly fusiform, straight or curved, without pappus, the outer persistent, stellately patent, smooth, the inner strongly curved, caducous, often hispidulous.

from: Meikle in Taxon 28: 133-141. 1979.

Distribution

Africa: Algeria (Algerianative); Canary Is. (Canary Is.native: doubtfully native); Egypt (Egyptnative); Libya (Libyanative); Madeira (Madeiranative); Morocconative; Tunisia (Tunisianative) Asia-Temperate: Cyprus (Cyprusnative); East Aegean Is. (East Aegean Is.native); Iran (Irannative); Iraq (Iraqnative); Lebanon-Syria (Lebanonnative, Syrianative); North Caucasusnative (Dagestannative, Krasnodarnative); Palestine (Israelnative, Jordannative); Saudi Arabia (Saudi Arabianative); Sinai (Sinainative); Transcaucasus (Abkhaziyanative, Adzhariyanative, Armenianative, Azerbaijannative, Georgianative); Turkey (Turkeynative) Europe: Albania (Albanianative); Baleares (Balearesnative); Bulgaria (Bulgarianative); Corse (Corsenative); Czechoslovakia (Czech Republicintroduced); Francenative; Germany (Germanyintroduced: adventitious (casual)); Greece (Greecenative); Italynative; Kriti (Kritinative); Krym (Krymnative); Poland (Polandintroduced: adventitious (casual)); Portugal (Portugalnative); Sardegna (Sardegnanative); Sicilynative (Maltanative, Sicilynative); Spain (Spainnative); Turkey-in-Europe (Turkey-in-Europenative); Ukraine (Ukrainenative); Yugoslavia (Bosnia-Herzegovinanative, Croatianative, Montenegronative, Slovenianative) Northern America: California (Californiaintroduced)

Systematics

Rhagadiolus is one of the genera of the Cichorieae without a pappus. Lacking thus one the more important diagnostic features, the placement of these genera provided particular problems. As in other such cases, molecular phylogenetic analysis revealed a rather different systematic position of Rhagadiolus compared to the previous, morphology-based classifications: while from Stebbins (1953) over Bremer (1994) to Lack (2006) the genus was placed in subtribe Hypochaeridinae, thus among Hypochaeris, Picris and Leontodon, molecular analyses have indicated (Whitton & al. 1995) or shown (Enke & Gemeinholzer 2008) that Rhagadiolus is a member of subtribe Crepidinae and close to Lapsana (s.str.) and Crepis. The results obtained by Enke & Gemeinholzer (2008) clearly show that both Rhagadiolus and Lapsana are even nested within Crepis, being sister to the "Lagoseris clade" of Crepis. As has been concluded by Enke (2009: 236), based on the currently available morphological, cytological, palynological, phytochemical and molecular results, "no argument could be found to encourage an exclusion of the species of the Lagoseris group from Crepis [which would then place Rhagadiolus and Lapsana outside Crepis and make Crepis s.str. monophyletic]; neither could any convincing argument be found to merge Lapsana and Rhagadiolus into Crepis". Enke (2009: 236) therefore suggests "to preserve the current generic circumscription of Crepis, even though it would be paraphyletic from a molecular point of view, until further evidence emerges", whereas "to include Lapsana and Rhagadiolus seems inappropriate given the morphological distinctness of both genera".

Rhagadiolus is treated as a genus comprising either one or two species. Meikle (1979) decidely advocated the distinction of two species against a long tradition of usually merging or separating them at infraspecific ranks only, proving that the concepts of the two taxa have been blurred by frequent confusion and misconception. Meikle (1979) emphasised the number and indumentum of the inner phyllaries as crucial diagnostic features and although his key seems to work fairly well, an analysis of the extent of the geographical or ecological separation of the two species and of the extent of intergradation in their core diagnostic features is still wanting.

References


Bremer K. 1994: Asteraceae: cladistics & Classification. – Portland: Timber.

Enke N. 2009: Contributions towards a revised infrageneric classification of Crepis (Cichorieae, Compositae). – Willdenowia 39: 229?245.

Enke N. & Gemeinholzer B. 2008: Babcock revisited: new insights into generic delimitation and character evolution in Crepis L. (Compositae : Cichorieae) from ITS and matK sequence data. – Taxon 57: 756-768.

Lack H. W. 2006 [2007]: Cichorieae. Pp. 180?199 in: Kadereit J.W. & Jeffrey C. (ed.), The families and genera of vascular plants 8. – Berlin: Springer.

Meikle R. D. 1979: Rhagadiolus: a misunderstood genus. – Taxon 28: 133-141.

Stebbins G. L. 1953: A new classification of the tribe Cichorieae, family Compositae. – Madrono 12: 65-81.

Whitton J., Wallace R. S. & Jansen R. K. 1995: Phylogenetic relationships and patterns of character change in the tribe Lactuceae (Asteraceae) based on chloroplast DNA restriction site variation. ? Canad. J. Bot. 73: 1058-1073.

Common names

Albanian (Albania): RagadioleA,1; Arabic (Lebanon): رَغَدْيولُسB,1; Arabic (Syria): رَغَدْيولُسC,1; Bulgarian (Bulgaria): РагадиолусD,1; Czech (Czech Republic): KosatkaE,1; French (Corse): RhagadioleF,1; French (France): RhagadioleG,1; Hebrew (Israel): כּוֹכְבָןH,1, כוכבןH,1; Italian (Italy): RadicchioI,1; Swedish (Sweden): StjärnfibblorJ,1; Turkish (Turkey): ÇatlakçanakK
1. recommended

Chromosome numbers

Diploids, x = 5.L

Bibliography

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