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The Centaurea group is part of the Circum-Mediterranean Clade (CMC) of genus Centaurea subgenus Centaurea, a mainly Mediterranean plant group with more than 200 described species. The group is traditionally split on morphological basis into three sections: Centaurea, Phalolepis and Willkommia. This division, however, is doubtful, especially in light of molecular approaches. In this study we try to resolve this phylogenetic problem and to consolidate the circumscription and delimitation of the entire group against other closely related groups. We analyzed nuclear (internal transcribed spacer of the ribosomal genes) and chloroplast (rpl32-trnL intergenic spacer) DNA regions for most of the described species of the Centaurea group using phylogenetic and network approaches, and we checked the data for recombination. Phylogeny was used to reconstruct the evolution of the lacerate-membranaceous bract appendages using parsimony. The magnitude of incomplete lineage sorting was tested estimating the effective population sizes. Molecular dating was performed using a Bayesian approach, and the ancestral area reconstruction was conducted using the Dispersal-Extinction-Cladogenesis method. Monophyly of the Centaurea group is confirmed if a few species are removed. Our results do not support the traditional sectional division. There is a high incongruence between the two markers and between genetic data and morphology. However, there is a clear relation between geography and the structure of the molecular data. Diversification in the Centaurea group mainly took place during the Pliocene and Pleistocene. The ancestral area infered for the Circum-Mediterranean Clade of Centaurea is the Eastern Mediterranean, whereas for the Centaurea group it is most likely NW-Africa. The large incongruencies, which hamper phylogenetic reconstruction, are probably the result of introgression, even though the presence of incomplete lineage sorting as an additional factor cannot be ruled out. Convergent evolution of morphological traits may have led to incongruence between morphology-based, traditional systematics and molecular results. Our results also cast major doubts about current species delimitation., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Spinescence refers to the presence of sharp appendages of various origins with ecological, evolutionary or biogeographic significance. This research was conducted to explore patterns and adaptive processes of thorns, spines and prickles in the Italian flora. We compiled an inventory of 401 spiny plants taking into account the following attributes: type of spinescence, family, biological form, chorotype, bioclimate and habitat. Then, we evaluated the incidence of plants with each attribute, the co-occurrence of various types of spinescence, the associations among spinescence types and biological forms and families, the structure of data across spinescence types, thermotypes and habitats. The spatial distributions and the adaptive processes of plants with various types of spinescence revealed that these patterns are driven by evolutionary, biogeographic and ecological factors, thus supporting the hypothesis that interactive processes of selective pressures and phylogenetic constraints have influenced the evolution of spinescences. [ABSTRACT FROM AUTHOR]

A phylogenetic analysis was performed based on ITS DNA sequences of fourteen samples from different sources of six species of Salicornia , the three allied genera Arthrocnemum , Sarcocornia and Halocnemum of the same tribe Salicornieae , and other genera of the subfamily Salicornioideae used in previous studies. Bassia hirsuta , Camphorosma monspeliaca (subfamily Chenopodioideae ) and four species of Suaeda (subf. Suaedoideae ) were chosen as outgroups. Results show that the annual genus Salicornia is a sister group to the perennial genera Sarcocornia , Arthrocnemum and Halocnemum . Moreover, the phylogenetic analysis based on ITS results distinguished two groups of Salicornia species which fitted with ploidy level: one group consisted of diploid species, and the second of tetraploid ones. Sarcocornia and Arthrocnemum are shown to be closely related, even though the species investigated here exhibited an evident distance between their ITS sequences. On the basis of our results, these two genera should be united. Bienertia (already separated as Bienertieae ) was confirmed as probable outgroup to the subf. Salicornioideae , while Kalidium (subf. Salicornioideae , tribe Halopeplideae ) was an outgroup to the rest of the Salicornioideae (tribe Salicornieae ). The group Allenrolfea plus Halocnemum was the most basal of the tribe Salicornieae amongst those investigated in this study. The two samples of Halocnemum strobilaceum used in this work displayed numerous changes (transitions and transversions) in their respective sequences, probably related to their morphological and chorological differentiation. On the basis of our analysis, the most probable basal chromosome number for Salicornieae appears to be 2n = 18. The same number would also be the base number for the annual genus Salicornia and the perennial Arthrocnemum ( + Sarcocornia ), with polyploidy arising independently in the two groups. [ABSTRACT FROM AUTHOR]