Achene Characteristics of Turkish Centaurea (asteraceae) and Their Systematic Application

This article investigates the exomorphic characteristics of the achenes which are achene size, color, and surface pattern, and pappus length, and colour. All these characteristics in seven taxa of Asteraceae namely, C. aggregata Fisch. & C.A. Mey. ex DC. subsp. aggregata, C. sivasica Wagenitz, C. polypodiifolia Boiss. var. polypodiifolia, C. polypodiifolia Boiss. var. szowitziana (Boiss.) Wagenitz, C. iberica Trev. ex Spreng, C. urvillei DC. subsp. stepposa Wagenitz, and C. carduiformis DC. subsp. carduiformis var. carduiformis in are described, illustrated and compared. The results of SEM at higher magnification showed three types of achene surface patterns: glebulate-ruminate, smooth, and rugose. In these patterns, there were diagnostic characteristics and differences at the specific level for Centaurea. A key to the taxa has been provided on the basis of these achene characteristics. Introduction The genus Centaurea L. (Asteraceae) has about 800 species in the Mediterranean area with SW Asia as its center of diversity (Wagenitz and Hellwig 1996). The genus was revised by Wagenitz (1975) for the Flora of Turkey in which 172 species plus six imperfectly known species were accepted. Turkey is one of the main centers of diversity of the genus (Wagenitz 1975). Here it is the third largest genus in terms of species number in Turkey. Centaurea s.l. has 217 species and endemism ratio is 66.8% in Turkey (Wagenitz 1975, Davis 1988, Güner et al. 2000, Özhatay et al. 2006, 2009, 2011). Recently, Centaurea L. has been divided into four genera (Wagenitz and Hellwig 2000, Greuter 2003a,b). The revised genera are Centaurea, Rhaponticoides Vaill., Psephellus Cass. and Cyanus Mill. The traditional delimitation of Centaurea as a genus is problematical, because it results obviously in a non-monophyletic taxon (Garcia-Jacas et al. 2000, 2001). Therefore, since Wagenitz (1955) there has been increased interest in the phylogeny and evolution of characters of "Centaurea" and the subtribe Centaureinae, including floral and achene micromorphology, pollen morphology, karyology and as the most promising approach, DNA sequences (Bancheva and Greilhuber 2006). This study examined the exomorphic characteristics of 7 Centaurea sensu lato seeds by using Scanning Electron Microscope (SEM) to highlight achene surface ornamentation. Materials and Method Mature achenes of 7 taxa of the genus Centaurea collected from their natural habitats in Turkey in 2012. The specimens collected were kept in the Herbarium (ISTE) of the Department of Pharmaceutical Botany Herbarium, Istanbul University (ISTE). The localities and voucher numbers of the taxa studied are given in Table 1. During Scanning Electron Microscopy (SEM), mature achenes (2 3) from each of the taxa were selected and mounted onto stubs with doublesided adhesive tape, and were then coated with gold. The achene surfaces were examined from the *Author for correspondence: .