INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY ISSN Print: 1560–8530; ISSN Online: 1814–9596 09–174/MHB/2009/11–5–553–558 http://www.fspublishers.org Full Length Article To cite this paper: Hayat, M.Q., M. Ashraf M.A. Khan, G. Yasmin, N. Shaheen and S. Jabeen, 2009. Phylogenetic relationships in Artemisia spp. (Asteraceae) based on distribution of foliar trichomes. Int. J. Agric. Biol., 11: 553–558 Phylogenetic Relationships in Artemisia spp. (Asteraceae) Based on Distribution of Foliar Trichomes MUHAMMAD QASIM HAYAT 1 , MUHAMMAD ASHRAF†, MIR AJAB KHAN, GHAZALAH YASMIN, NIGHAT SHAHEEN, AND SHAZIA JABEEN‡ Department of Plant Sciences, Quaid-i-Azam University, Islamabad, Pakistan †NUST Center of Virology and Immunology, National University of Science and Technology, Rawalpindi, Pakistan ‡National Center of Excellence in Geology, University of Peshawar, Peshawar, Pakistan 1 Corresponding author’s e-mail: mqasimhayat@hotmail.com ABSTRACT The phylogenetic relationships within the genus Artemisia have been very controversial and need throughout investigations. In continuation to the previous paper, here we report the phylogenetic relationships in the genus Artemisia based on the foliar trichomes using light microscopy and scanning electron microscopy. The data from 24 taxa was analyzed for its phylogeny. In addition, eight new types of foliar trichomes in the genus were described. This study also revealed that foliar trichomes of the genus Artemisia are good taxonomic markers and can be utilized to resolve the taxonomic conflicts within the genus. Key Words: Artemisia; Seriphidium; Anthemideae; Asteraceae; Anatomy; Trichomes; Phylogeny INTRODUCTION Artemisia L. is one of the largest genera of the family Asteraceae. Its members are wind pollinated and mainly distributed in temperate areas of mid to high latitudes of the northern hemisphere, colonize in arid and semiarid environments, and only few representatives are found in southern hemisphere (McArthur & Plummer, 1978; Valles & McArthur, 2001). Many species of the genus have economic value as medicines, food, forage, ornamentals or soil stabilizers in disturb habitats; some taxa are toxic or allergenic and some others are invasive weeds, which can adversely affect harvests (Pareto, 1985; Tan et al., 1998; Hayat et al., 2009a & b). Except few annuals or biannual, most Artemisia species are perennial (Valles et al., 2003). The genus Artemisia is also considered as indicator of steppe climate (Erdtman, 1952) and moderate precipitation (El-Moslimany, 1990). Classically the genus has been divided into four groups, which has been treated as sections or subgenera; Absinthium (Tournefort) de Cand., Artemisia Tournefort (=Abrotanum Besser), Dracunculus Besser, Seriphidium Besser (Hooker, 1881; Martin et al., 2001 & 2003). McArthur et al. (1981) proposed a new group Tridantatae (Rydb.) McArthur, which is endemic to North America. Ling (1982, 1991a & b, 1995a & b) separated Seriphidium (Besser ex Hooker) as independent genus. Bremer and Humphries (1993) and Bremer (1994) accepted this separation. But Kornkven et al. (1998), Torrell et al. (1999) and Watson et al. (2002) in their molecular studies again merged Seriphidium with Artemisia. Nonetheless classification of Artemisia and relationships among its different taxa are still controversial. Scotland et al. (2003) opined that rigorous and critical anatomical studied of fewer morphological characters in the context of molecular phylogenies is fruitful to integrating the strengths of morphological data with those of sequence data. Since the micromorphological characteristics of foliar trichomes play an important role in plant taxonomy, especially of particular groups at generic and specific levels, attention of plant morphologists and systematists has been mainly attracted to resolve the taxonomic conflicts (Hardin, 1979; Fang & Fan, 1993). Although many studies conducted on the histochemistry of the secretory products of the glandular trichomes of Artemisia (Smith & Kreitner, 1983; Slone & Kelsey, 1985; Ascensao & Pais, 1987; Duke & Paul, 1993; Duke et al., 1994), little is known about the systematic significance of trichomes in Artemisia. In the present paper, we report the micromorphological characteristics of foliar trichomes in Artemisia using light microscopy (LM) and scanning electron microscopy (SEM). The specific objectives were to: (a) identify and compare the micromorphological characteristics of foliar trichomes in different species of this genus and (b) reconstruct the phylogenetic relationships among different taxa of Artemisia based on characteristics of foliar trichomes. MATERIALS AND METHODS All details about the origin and collection of leaf material, processing of the tissues, basic terminology and studies of the foliar trichomes were essentially the same as