ORIGINAL ARTICLE A morphometric analysis and taxonomic study of Panax bipinnatifidus Seem. (Araliaceae) species complex from Sikkim Himalaya, India Shiva K. Sharma • Maharaj K. Pandit Received: 9 July 2010 / Accepted: 26 June 2011 Ó Springer-Verlag 2011 Abstract The taxonomic position of Panax bipinnatifidus is controversial and problematic. To infer inter- or intra- specific morphological relationship in Panax bipinnatifidus and its allies—P. sikkimensis and P. sokpayensis, we car- ried out a phenetic study of these taxa, based on thirteen morphological characters (eight quantitative and five qualitative), using univariate and multivariate analysis. The results obtained from the principle component analy- sis (PCA) and cluster analysis (CA) revealed lack of taxonomic differences between Panax bipinnatifidus and P. sikkimensis, whereas P. sokpayensis showed distinct morphological features. Discriminant analysis (DA) of the quantitative morphological characters also did not reveal any dissimilarity between Panax bipinnatifidus and P. sikkimensis. There were no differences between majority of the morphological characters of Panax bipinnatifidus and P. sikkimensis except for the presence of pinnate leaflets and absence of bracts in the latter. The lack of differences in morphological characters of Panax bipinn- atifidus and P. sikkimensis suggest that these two taxa are part of the same species complex. Our field studies show that Panax binnatifidus does not occur as an independent species anywhere in nature, but always shows a congeneric association with P. sikkimensis. In addition, the morpho- type of undivided leaflets (P. sikkimensis) is more normal and common than the morphotype of pinnate or bipinnate leaflets (P. bipinnatifidus) in natural populations. Following the principle of priority of the International Code of Botanical Nomenclature we conclude that Panax bipinn- atifidus is a distinct species, while P. sikkimensis is a syn- onym of P. bipinnatifidus in Indian Himalaya. Based on the present investigations we propose that Panax bipinnatifidus Seem. should be given recognition and priority for the specific rank as opposed to the views of earlier workers. A taxonomic key of the studied taxa is provided. Keywords Taxonomy Á Phenetic analysis Á Panax bipinnatifidus Á Sympatric distribution Á Sikkim Himalaya Introduction The most recent taxonomic accounts of Panax L. suggest that the genus comprises 16–18 species with disjunct distribution in the North America and eastern Asia (Wen and Zimmer 1996; Wen 2001). Panax quinquefolius L. and P. trifolius L. grow wild in the eastern North America (Burkill 1902; Graham 1966; Hu et al. 1980; Proctor and Bailey 1987), while other 16 species of Panax are distributed in the eastern central Asia (Hu 1976; Wen 2001). Maximum species diversity in Panax is reported from eastern, south- western and central provinces of China, Central to Eastern Himalaya (Nepal, Bhutan and India) and some parts of South-East Asia (Burkill 1902; Hara 1970; Yang 1981; Wen and Zimmer 1996). The lack of congruence in morpholog- ical characters among Panax species has made the taxo- nomic delimitation in the genus rather controversial (Graham 1966; Hara 1970; Bennet and Sharma 1983; Wen and Zimmer 1996; Yoo et al. 2001). Phylogenetic studies have revealed three distinct clades, viz. (1) Panax trifolius, S. K. Sharma Á M. K. Pandit Centre for Interdisciplinary Studies of Mountain and Hill Environment (CISMHE), University of Delhi, ARC Building, Patel Marg, Delhi 110007, India M. K. Pandit (&) Department of Environmental Studies, University of Delhi, Delhi 110007, India e-mail: rajkpandit@gmail.com 123 Plant Syst Evol DOI 10.1007/s00606-011-0501-8